Vasya used to be an accountant before the war began and he is one of the few who knows how to operate a computer, so he was assigned as the programmer.

We all know that programs often store sets of integers. For example, if we have a problem about a weighted directed graph, its edge can be represented by three integers: the number of the starting vertex, the number of the final vertex and the edge's weight. So, as Vasya was trying to represent characteristics of a recently invented robot in his program, he faced the following problem.

Vasya is not a programmer, so he asked his friend Gena, what the convenient way to store n integers is. Gena used to code in language X-- and so he can use only the types that occur in this language. Let's define, what a "type" is in language X--:

  * First, a type is a string "int". 
  * Second, a type is a string that starts with "pair", then followed by angle brackets listing exactly two comma-separated other types of language X--. This record contains no spaces. 
  * No other strings can be regarded as types. 



More formally: type := int | pair<type,type>. For example, Gena uses the following type for graph edges: pair<int,pair<int,int>>.

Gena was pleased to help Vasya, he dictated to Vasya a type of language X--, that stores n integers. Unfortunately, Gena was in a hurry, so he omitted the punctuation. Now Gena has already left and Vasya can't find the correct punctuation, resulting in a type of language X--, however hard he tries.

Help Vasya and add the punctuation marks so as to receive the valid type of language X--. Otherwise say that the task is impossible to perform.

Input

The first line contains a single integer n (1 ≤ n ≤ 105), showing how many numbers the type dictated by Gena contains.

The second line contains space-separated words, said by Gena. Each of them is either "pair" or "int" (without the quotes).

It is guaranteed that the total number of words does not exceed 105 and that among all the words that Gena said, there are exactly n words "int".

Output

If it is possible to add the punctuation marks so as to get a correct type of language X-- as a result, print a single line that represents the resulting type. Otherwise, print "Error occurred" (without the quotes). Inside the record of a type should not be any extra spaces and other characters. 

It is guaranteed that if such type exists, then it is unique.

Note that you should print the type dictated by Gena (if such type exists) and not any type that can contain n values.

Examples

Input

3
pair pair int int int


Output

pair&lt;pair&lt;int,int&gt;,int&gt;

Input

1
pair int


Output

Error occurred
//package cdr;
import java.util.*;
import java.math.*;
import java.io.*;

public class Luck{
	public static InputReader sc;
    public static PrintWriter out;
    public static final int MOD = (int) (1e9 + 7);
    static TreeSet<Integer>[] adj;
    static boolean[] visited;
    static String[] A;
    public static void main(String[] args){
    	//sc=new InputReader(System.in);	
    	Scanner in=new Scanner(System.in);
    	out=new PrintWriter(System.out);
    	int n=in.nextInt();
    	in.nextLine();
    	String str=in.nextLine();
    	A=str.split(" ");
    	/*for(int i=0;i<A.length;i++){
    		out.println("A: "+A[i]);
    	}*/
    	if(dfs(0)==A.length){
    		dfs2(0);
    	}
    	else{
    		out.println("Error occurred");
    	}
    	in.close();
    	out.close();
    }
    
    static int dfs(int id){
    	if(id>=A.length) return id+100;
    	if(A[id].endsWith("int")){
    		return id+1;
    	}
    	else{
    		int next=dfs(id+1);
    		next=dfs(next);
    		return next;
    	}
    }
    static int dfs2(int id){
    	if(id>=A.length) return id+100;
    	if(A[id].endsWith("int")){
    		out.print("int");
    		return id+1;
    	}
    	else{
    		out.print("pair<");
    		int next=dfs2(id+1);
    		out.print(",");
    		next=dfs2(next);
    		out.print(">");
    		return next;
    	}
    }
    static int gcd(int a,int b){
    	if(b==0){
    		return a;
    	}
    	return gcd(b,a%b);
    	
    }
    static int lcm(int a,int b){
    	int g;
    	if(a<b){
    		g=gcd(b,a);
    	}
    	else{
    		g=gcd(a,b);
    	}
    	return (a*b)/g;
    }
    
    static boolean isPrime(int n){
    	 if (n == 2)
    	        return true;
    	    for (long i = 2; i * i <= n; i++) {
    	        if (n % i == 0)
    	            return false;
    	    }
    	    return true;
    }
    
    static void shuffle(int[] A){
    	for(int i=A.length-1;i>0;i--){
    		int j=(int)(Math.random()*(i+1));
    		int temp=A[j];
    		A[j]=A[i];
    		A[i]=temp;
    	}
    }
    
	public static class Node implements Comparable<Node>{
	    int v;
	    int d;
	    public Node(){
	    	;
	    }
	    public Node (int v, int d) {
	    	this.d = d;
	        this.v = v;
	        
	    }
	    
	    public void print() {
	        out.println(v + " " + d + " ");
	    }
	   
	    public int compareTo(Node n1){
	    	return this.d-n1.d;
	    }
	}

	public static BigInteger pow(BigInteger base, BigInteger exp) {
	    if(exp.equals(new BigInteger(String.valueOf(0)))){
	        return new BigInteger(String.valueOf(1));
	    }    
	    if(exp.equals(new BigInteger(String.valueOf(1))))
	        return base;
	    BigInteger temp=exp.divide(new BigInteger(String.valueOf(2)));
	    BigInteger val = pow(base, temp);
	    BigInteger result = val.multiply(val);
	    result=result.remainder(new BigInteger(String.valueOf(MOD)));
	    BigInteger AND=exp.and(new BigInteger(String.valueOf(1)));
	    if(AND.equals(new BigInteger(String.valueOf(1)))){
	        result = result.multiply(base);
	        result=result.remainder(new BigInteger(String.valueOf(MOD)));
	    }    
	    return result;
	}
	    
	static class InputReader {

	    private InputStream stream;
	    private byte[] buf = new byte[8192];
	    private int curChar, snumChars;
	    private SpaceCharFilter filter;

	    public InputReader(InputStream stream) {
	        this.stream = stream;
	    }

	    public int snext() {
	        if (snumChars == -1)
	            throw new InputMismatchException();
	        if (curChar >= snumChars) {
	            curChar = 0;
	            try {
	                snumChars = stream.read(buf);
	            } catch (IOException e) {
	                throw new InputMismatchException();
	            }
	            if (snumChars <= 0)
	                return -1;
	        }
	        return buf[curChar++];
	    }

	    public int nextInt() {
	        int c = snext();
	        while (isSpaceChar(c))
	            c = snext();
	        int sgn = 1;
	        if (c == '-') {
	            sgn = -1;
	            c = snext();
	        }
	        int res = 0;
	        do {
	            if (c < '0' || c > '9')
	                throw new InputMismatchException();
	            res *= 10;
	            res += c - '0';
	            c = snext();
	        } while (!isSpaceChar(c));
	        return res * sgn;
	    }

	    public long nextLong() {
	        int c = snext();
	        while (isSpaceChar(c))
	            c = snext();
	        int sgn = 1;
	        if (c == '-') {
	            sgn = -1;
	            c = snext();
	        }
	        long res = 0;
	        do {
	            if (c < '0' || c > '9')
	                throw new InputMismatchException();
	            res *= 10;
	            res += c - '0';
	            c = snext();
	        } while (!isSpaceChar(c));
	        return res * sgn;
	    }

	    public int[] nextIntArray(int n) {
	        int a[] = new int[n];
	        for (int i = 0; i < n; i++)
	            a[i] = nextInt();
	        return a;
	    }

	    public String readString() {
	        int c = snext();
	        while (isSpaceChar(c))
	            c = snext();
	        StringBuilder res = new StringBuilder();
	        do {
	            res.appendCodePoint(c);
	            c = snext();
	        } while (!isSpaceChar(c));
	        return res.toString();
	    }

	    public boolean isSpaceChar(int c) {
	        if (filter != null)
	            return filter.isSpaceChar(c);
	        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
	    }

	    public interface SpaceCharFilter {
	        public boolean isSpaceChar(int ch);
	    }
	}

}

