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 B {
      static FastScanner sc;
      static PrintWriter pw;
  
      public static void main(String[] args) throws Exception{
          sc = new FastScanner();
          pw = new PrintWriter(System.out);
          
          try{
  
              int T = sc.ni();
              while(T-->0){
                  long n = sc.nl();
                  long k = sc.nl();
                  long m = 1000000007;
                  long ans = 0;
                  long p = 1;
                  for(int i=0; i<31; i++){
                      if((k&(1<<i))!=0){
                          ans = (ans + p)%m;
                      }
                      p = (p*n)%m;
                  }
                  pw.println(ans);
              }
  
          }catch(Exception e){
              return;
          }
  
          pw.close();
      }
  
      static class FastScanner {
          BufferedReader br;
          StringTokenizer st;
   
          public FastScanner() {
              br = new BufferedReader(new InputStreamReader(System.in), 32768);
              st = null;
          }
   
          String next() {
              while (st == null || !st.hasMoreElements()) {
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              return st.nextToken();
          }
   
          int ni() {
              return Integer.parseInt(next());
          }
  
          int[] intArray(int N) {
              int[] ret = new int[N];
              for (int i = 0; i < N; i++)
                  ret[i] = ni();
              return ret;
          }
   
          long nl() {
              return Long.parseLong(next());
          }
  
          long[] longArray(int N) {
              long[] ret = new long[N];
              for (int i = 0; i < N; i++)
                  ret[i] = nl();
              return ret;
          }
  
          double nd() {
              return Double.parseDouble(next());
          }
   
          String nextLine() {
              String str = "";
              try {
                  str = br.readLine();
              } catch (IOException e) {
                  e.printStackTrace();
              }
              return str;
          }
      }
  
  }