Hands that shed innocent blood!

There are n guilty people in a line, the i-th of them holds a claw with length Li. The bell rings and every person kills some of people in front of him. All people kill others at the same time. Namely, the i-th person kills the j-th person if and only if j < i and j ≥ i - Li.

You are given lengths of the claws. You need to find the total number of alive people after the bell rings.

Input

The first line contains one integer n (1 ≤ n ≤ 106) — the number of guilty people.

Second line contains n space-separated integers L1, L2, ..., Ln (0 ≤ Li ≤ 109), where Li is the length of the i-th person's claw.

Output

Print one integer — the total number of alive people after the bell rings.

Examples

Input

4
0 1 0 10


Output

1


Input

2
0 0


Output

2


Input

10
1 1 3 0 0 0 2 1 0 3


Output

3

Note

In first sample the last person kills everyone in front of him.
import java.io.*;
import java.util.*;
import java.math.*;
//public 
class Main{
    //static variable
    static final int mod = (int) 1e9 + 7;
    static final double eps = 1e-6;
    static final double pi = Math.PI;
    static final long inf = Long.MAX_VALUE / 2;

    // .......static class
  static class Pair{
      int key,value;
      Pair(int key,int value){
        this.key=key;
        this.value=value;
      }
      int Key(){
        return key;
      }
      int Value(){
        return value;
      }
  }
  static class mycomparator implements Comparator<Pair>{
     @Override
     public int compare(Pair o1,Pair o2){
      Integer key1=o1.Key(),key2=o2.Key();
          return key1.compareTo(key2);
     }
  }
    
//.............staic class end.
  
    BufferedReader br;
    PrintWriter out;
    public static void main(String[] args) {
    new Main().main1();
 
  }
  void main1()
  {
    try{
       
        br=new BufferedReader(new InputStreamReader(System.in));
        out=new PrintWriter(System.out);
      int t=1;
     // t=ii();
      while(t-->0){

        //........solution start

        int n=ii();
        int[] a=iint();
        int dead=0;
        int l=Math.max(0,n-1-a[n-1]),r=n-2;
        for (int i=n-2;i>=0 ;i-- ) {
            if(a[i]==0)
            continue;
           int l1=Math.max(0,i-a[i]),r1=i-1;

            
            if(l>r1)
            {
              dead+=(r-l+1);
              l=l1;
              r=r1;
              //System.out.println("l and r "+l+" "+r);
              continue;
            }
            if(l1<l)
            {
              l=l1;
            }
            // System.out.println("l and r "+l+" "+r);
            
        }
        
        dead+=(r-l+1);
        System.out.println(n-dead);

  
        









        //..........solution end.

     }
     out.flush();
     out.close(); 
    }
    catch(Exception e){
        e.printStackTrace();}    
  }


  // ...............required method.




  //................end.
  
  
   //..............input method start. 
    int getmax(int a[]){
      int n=a.length;
      int max=a[0];
      for (int i=1;i<n ;i++ ) {
        max=Math.max(a[i],max);
      }
      return max;
    }
     int getmin(int a[]){
      int n=a.length;
      int min=a[0];
      for (int i=1;i<n ;i++ ) {
        min=Math.min(a[i],min);
      }
      return min;
    }

    int[] iint() throws IOException{
      String line[]=br.readLine().split(" ");
      int[] a=new int[line.length];
      for (int i=0;i<line.length ;i++ ) {
        a[i]=Integer.parseInt(line[i]);
      }
      return a;
    }
    long[] ilong() throws IOException{
      String line[]=br.readLine().split(" ");
      long[] a=new long[line.length];
      for (int i=0;i<line.length ;i++ ) {
        a[i]=Long.parseLong(line[i]);
      }
      return a;
    }
    double[] idouble() throws IOException{
      String line[]=br.readLine().split(" ");
      double[] a=new double[line.length];
      for (int i=0;i<line.length ;i++ ) {
        a[i]=Long.parseLong(line[i]);
      }
      return a;
    }
    long li() throws IOException{
      
      return Long.parseLong(br.readLine());
    }
    int ii() throws IOException{
      
      return Integer.parseInt(br.readLine());
    }
    double di() throws IOException{
      return Double.parseDouble(br.readLine());
    }
    char ci() throws IOException{
      return (char)br.read();
    }
    String si() throws IOException{
       return br.readLine();
    }
    String[] isa(int n) throws IOException{
        String at =si();
        return at.split(" ");
    }

    double[][] idm(int n, int m) throws IOException{
        double a[][] = new double[n][m];
        for (int i = 0; i < n; i++) {
          double[] temp=idouble();
          for (int j = 0; j < m; j++) a[i][j] = temp[j];
        }
        return a;
    }

    int[][] iim(int n, int m) throws IOException{
        int a[][] = new int[n][m];
        for (int i = 0; i < n; i++) {
          int[] temp=iint();
          for (int j = 0; j < m; j++) a[i][j] =temp[j];
        }
        return a;
    }
    long[][] ilm(int n, int m) throws IOException{
       long a[][] = new long[n][m];
        for (int i = 0; i < n; i++) {
          long[] temp=ilong();
          for (int j = 0; j < m; j++) a[i][j] =temp[j];
        }
        return a;
    }
    //..............input methods end;
    
} 