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

int main(int argc, char* argv[]) {
	FILE* uno = fopen(argv[1], "r");
	FILE* due = fopen(argv[2], "r");
	FILE* tre = fopen(argv[3], "w");
	int i = 1;
	char a, b;
	while(i != EOF) {
		i = fscanf(uno, "%c", &a);
		fscanf(due, "%c", &b);
		if(i != EOF) {
			fprintf(tre, "%c", a^b);
		}
	}
	fclose(uno);
	fclose(due);
	fclose(tre);

	return 0;
}