new_contents: #!/usr/bin/env python3
  # -*- coding: utf-8 -*-
  
  def solve():
      L, N = input().split(' ')
      N = int(N)
      result = ''
  
      while N > 0:
          N -= 1
          result = L[N % len(L)] + result
          N = int(N / len(L))
  
      return result
  
  def main():
      T = int(input())
      for i in range(T):
          print('Case #{i}: {answer}'.format(i=i+1, answer=solve()))
  
  if __name__ == '__main__':
      main()
  
subject: Add solution v2 for Labelmaker.