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;
  vector<vector<int> > adj;
  int e1, e2;
  int N, M;
  long long int gcd(long long int a, long long int b);
  long long int lcm(long long int a, long long int b);
  long long int CEIL(long long int a, long long int b);
  long long int power_mod(long long int a, long long int b, long long int mod);
  vector<long long int> powers;
  void pre() {
    long long int p = 1;
    while (p <= 1e9) {
      powers.push_back(p);
      p *= 2;
    }
  }
  void solve(long long int input) {
    long long n, k;
    cin >> n >> k;
    long long p = 1;
    long long int z = 0;
    while (p <= k) p *= 2, ++z;
    if (p == k) {
      cout << power_mod(n, z, 1e9 + 7) << "\n";
      return;
    }
    long long ans = 0;
    const long long int mod = 1e9 + 7;
    long long int pos;
    while (1) {
      pos = upper_bound(powers.begin(), powers.end(), k) - powers.begin();
      pos--;
      (ans += power_mod(n, pos, mod)) %= mod;
      k -= powers[pos];
      if (k <= 0) break;
    }
    cout << ans << endl;
  }
  signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    long long int x = 1;
    pre();
    cin >> x;
    for (long long int i = 1; i <= x; i++) {
      solve(i);
    }
    return 0;
  }
  long long int gcd(long long int a, long long int b) {
    if (b == 0) return a;
    return gcd(b, a % b);
  }
  long long int lcm(long long int a, long long int b) {
    return (a / gcd(a, b)) * b;
  }
  long long int CEIL(long long int a, long long int b) { return (a + b - 1) / b; }
  long long int power_mod(long long int x, long long int y, long long int mod) {
    long long int res = 1;
    x = x % mod;
    while (y > 0) {
      if (y & 1) res = (res * x) % mod;
      y = y >> 1;
      x = (x * x) % mod;
    }
    return res;
  }
  