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.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.StringTokenizer;
  
  public class B {
      static class RealScanner {
          BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
          StringTokenizer st = new StringTokenizer("");
  
          String next() {
              while (!st.hasMoreTokens())
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              return st.nextToken();
          }
  
          int nextInt() {
              return Integer.parseInt(next());
          }
  
          int[] readArray(int n) {
              int[] a = new int[n];
              for (int i = 0; i < n; i++) a[i] = nextInt();
              return a;
          }
  
          long nextLong() {
              return Long.parseLong(next());
          }
      }
  
      static int MOD = (int) (1e9 + 7);
  
      public static long Math_pow(long val1, long val2) {  //pow of middle && fast
          if (val2 == 0) {
              return 1;
          }
          if (val2 == 1) {
              return val1 % MOD;
          }
          long middle_pow = Math_pow(val1, val2 / 2);
          long tot = ((middle_pow % MOD) * (middle_pow % MOD)) % MOD;
          if (val2 % 2 != 0) {
              tot = ((tot % MOD) * (val1 % MOD)) % MOD;
          }
          return tot % MOD;
      }
  
      public static void main(String[] args) {
          PrintWriter out = new PrintWriter(System.out);
          RealScanner sc = new RealScanner();
          int t = sc.nextInt();
          while (t-- > 0) {
              long a, b;
              a = sc.nextLong();
              b = sc.nextLong();
              long tot = 0;
              long idx = 0;
              while (b > 0) {
                  if (b % 2 != 0) {
                      tot += (Math_pow(a, idx) % MOD);
                      b--;
                  }
                  b /= 2;
                  idx++;
              }
              out.println(tot % MOD);
          }
          out.flush();
          out.close();
      }
  }
  