# https://yukicoder.me/problems/no/3610

import math

MOD = 10 ** 9 + 7

def main():
    N = int(input())
    S = input()
    x, c = input().split()

    x = int(x) - 1
    s_array = [s for s in S]
    s_array[x] = c

    print("".join(s_array))




    





if __name__ == "__main__":
    main()