"""
Task
Read a given string, change the character at a given index and then print the modified string.
Function Description

Complete the mutate_string function in the editor below.

mutate_string has the following parameters:

string string: the string to change
int position: the index to insert the character at
string character: the character to insert
Returns

string: the altered string
Input Format

The first line contains a string, string .
The next line contains an integer position, the index location and a string character, separated by a space.

Sample Input

STDIN           Function
-----           --------
abracadabra     s = 'abracadabra'
5 k             position = 5, character = 'k'


Sample Output

abrackdabra


"""


def mutate_string(string, position, character):

    string_list = list(string)
    string_list[position] = character


    return "".join(string_list)

if __name__ == '__main__':
    s = input()
    i, c = input().split()
    s_new = mutate_string(s, int(i), c)
    print(s_new)