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 main(int argc, const char* argv[]) {
    int t;
    cin >> t;
    while (t--) {
      long long n, k;
      cin >> n >> k;
      queue<bool> q;
      long long two_degree = 2;
      while (k) {
        if (k % two_degree != 0)
          q.push(true);
        else
          q.push(false);
        k -= k % two_degree;
        two_degree <<= 1;
      }
      long long result = 0;
      long long n_degree = 1;
      while (!q.empty()) {
        if (q.front()) result += n_degree;
        n_degree *= n;
        n_degree %= 1000000007;
        result %= 1000000007;
        q.pop();
      }
      cout << result << endl;
    }
  }
  