#include <stdlib.h>
#include <stdio.h>


int main (int argc, char ** argv){

int x=0;
int first=0;
int second=0;

	if (argc!=3) {
		printf("usage: swap <char1> <char2>\n");
		exit(1);
	}

	first = argv[1][0];
	second= argv[2][0];

		while ((x=getchar())!=-1){
			
			if (x==first) x=second;
			else if (x==second) x=first;
			putchar(x);
		}

return 0;
}