GIVEN AN INPUT STRING S AND TWO CHARACTERS C1 AND C2, YOU NEED TO REPLACE EVERY OCCURRENCE OF CHARACTER C1 WITH CHARACTER C2 IN THE GIVEN STRING. DO THIS RECURSIVELY.

#include <iostream>
using namespace std;
void replaceCharacter(char input[], char c1, char c2) {
    /* Don't write main().
     * Don't read input, it is passed as function argument.
     * No need to print or return the output. 
     * Change in the given input string itself.
     * Taking input and printing output is handled automatically.
     */
    if(input[0]=='\0')
        return;
    if(input[0]!=c1)
        replaceCharacter(input+1,c1,c2);
    else{
        input[0]=c2;
        replaceCharacter(input+1,c1,c2);
    }
}

int main() {
    char input[1000000];
    char c1, c2;
    cin >> input;
    cin >> c1 >> c2;
    replaceCharacter(input, c1, c2);
    cout << input << endl;
}