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

#define BUFFER_SIZE 512

int main(int argc, char **argv)
{
    char data[BUFFER_SIZE];
    char map[256];
    int i;

    for (i = 0; i < 256; i++) {
	map[i] = (i >= 32 && i <= 127) ? i : 0;
    }
    map['\n'] = '\n';

    if (argc == 3) {
	char *p = argv[1];
	char *q = argv[2];
	for (; *p; p++) {
	    map[(unsigned char) *p] = *q;
	    if (*q)
		q++;
	}
    }

    while (fgets(data, BUFFER_SIZE, stdin)) {
	int j = 0;
	for (i = 0; data[i]; i++) {
	    if (map[(unsigned char) data[i]]) {
		data[j] = map[(unsigned char) data[i]];
		j++;
	    }
	}
	data[j] = 0;
	fputs(data, stdout);
    }

    return EXIT_SUCCESS;
}