description: Theofanis really likes sequences of positive integers, thus his teacher (Yeltsa Kcir) gave him a problem about a sequence that consists of only special numbers.
  
  Let's call a positive number special if it can be written as a sum of different non-negative powers of n. For example, for n = 4 number 17 is special, because it can be written as 4^0 + 4^2 = 1 + 16 = 17, but 9 is not.
  
  Theofanis asks you to help him find the k-th special number if they are sorted in increasing order. Since this number may be too large, output it modulo 10^9+7.
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 10^4) — the number of test cases.
  
  The first and only line of each test case contains two integers n and k (2 ≤ n ≤ 10^9; 1 ≤ k ≤ 10^9).
  
  Output
  
  For each test case, print one integer — the k-th special number in increasing order modulo 10^9+7.
  
  Example
  
  Input
  
  
  3
  3 4
  2 12
  105 564
  
  
  Output
  
  
  9
  12
  3595374
  
  Note
  
  For n = 3 the sequence is [1,3,4,9...]
solution: import java.io.*;
  import java.util.*;
  
  public class Main {
          private static final int MOD = 1000000007;
          private static int add(long a, long b) { return (int) (((a+MOD)%MOD+(b+MOD)%MOD)%MOD); }
          private static int multiply(long a, long b) {
                  return (int) (((a%MOD)*(b%MOD))%MOD);
          }
          private static int power(long a, long b) {
                  long c = 1;
                  while(b > 0) {
                          if((b&1) > 0) {
                                  c = multiply(c, a);
                          }
                          a = multiply(a, a);
                          b >>= 1;
                  }
                  return (int) c;
          }
          public static void main(String[] args) throws IOException{
          //BufferedReader f = new BufferedReader(new FileReader("uva.in"));
          BufferedReader f = new BufferedReader(new InputStreamReader(System.in));
          PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
          int t = Integer.parseInt(f.readLine());
          while(t-- > 0) {
                  StringTokenizer st = new StringTokenizer(f.readLine());
                  int n = Integer.parseInt(st.nextToken());
                  int k = Integer.parseInt(st.nextToken());
                  char[] res = Integer.toBinaryString(k).toCharArray();
                  long ans = 0;
                  for(int i = 0; i < res.length; i++) {
                          if(res[i] == '1') {
                                  ans = add(ans, power(n, res.length-i-1));
                          }
                  }
                  out.println(ans);
          }
          f.close();
          out.close();
      }
  }
  