text: def mutate_string(string, position, character):
      l = list(string)
      l[position] = character
      string = ''.join(l)
      return string
  
  if __name__ == '__main__':
      s = input()
      i, c = input().split()
      s_new = mutate_string(s, int(i), c)
      print(s_new)
  