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: #include <bits/stdc++.h>
  using namespace std;
  int n, k, t;
  map<int, int> m;
  long long s, ss = 1;
  int main() {
    cin >> t;
    while (t--) {
      cin >> n >> k;
      for (int i = 0; i >= 0; i++) {
        if (k == 1) {
          m[i] = 1;
          for (int j = 1; j <= i; j++) {
            ss *= n;
            ss %= 1000000007;
          }
          s += ss;
          ss = 1;
          break;
        }
        if (k % 2 == 1) {
          m[i] = 1;
          for (int j = 1; j <= i; j++) {
            ss *= n;
            ss %= 1000000007;
          }
          s += ss;
          ss = 1;
        }
        k /= 2;
      }
      s %= 1000000007;
      cout << s << '\n';
      s = 0;
    }
  }
  