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.math.BigInteger;
  import java.util.*;
  
  public class q2 {
      static long mod = (long) Math.pow(10, 9) +7;
      static BigInteger MOD = new BigInteger(String.valueOf(mod));
      public static void main(String[] args) {
          int t = io.nextInt();
  
          StringBuilder sb = new StringBuilder();
          for (int i = 0; i < t; i++) {
              long n = io.nextLong();
              long k = io.nextLong();
              String s = Long.toBinaryString(k);
              /*System.out.println(s);*/
              BigInteger sum = BigInteger.ZERO;
              BigInteger temp = new BigInteger(String.valueOf(n));
              for (int l = 0; l < s.length(); l++) {
                  if(s.charAt(l) == '1'){
                      BigInteger s1 = temp.pow(s.length() - 1 - l);
                      s1 = s1.mod(MOD);
                      sum = sum.add(s1);
                      sum = sum.mod(MOD);
                  }
              }
              sb.append(sum).append(" \n");
          }
          sb.deleteCharAt(sb.length() - 1);
          System.out.print(sb);
  
      }
  
      static Kattio2 io = new Kattio2();
  }
  
  class Kattio2 extends PrintWriter {
      private BufferedReader r;
      private StringTokenizer st;
  
      // standard input
      public Kattio2() {
          this(System.in, System.out);
      }
  
      public Kattio2(InputStream i, OutputStream o) {
          super(o);
          r = new BufferedReader(new InputStreamReader(i));
      }
  
      // USACO-style file input
      public Kattio2(String problemName) throws IOException {
          super(new FileWriter(problemName + ".out"));
          r = new BufferedReader(new FileReader(problemName + ".in"));
      }
  
      // returns null if no more input
      public String next() {
          try {
              while (st == null || !st.hasMoreTokens())
                  st = new StringTokenizer(r.readLine());
              return st.nextToken();
          } catch (Exception e) {
          }
          return null;
      }
  
      public int nextInt() {
          return Integer.parseInt(next());
      }
  
      public double nextDouble() {
          return Double.parseDouble(next());
      }
  
      public long nextLong() {
          return Long.parseLong(next());
      }
  }
  
  