#include <string.h>
#include <stdio.h>

typedef struct {
    char areaCode[10];
    char exchangeCode[40];
} PhoneNumber;

int main() {
    PhoneNumber a, b;
    scanf("%s %s", a.areaCode, a.exchangeCode);
    scanf("%s %s", b.areaCode, b.exchangeCode);
    if (strcmp(a.areaCode, b.areaCode) == 0) {
        printf("%s", b.exchangeCode);
    } else {
        printf("%s%s", b.areaCode, b.exchangeCode);
    }
    return 0;
}