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

int main(void){
    char SA[100], SB[100], PA[100000], PB[100000], XA, XB;
    scanf("%s %s %c %s %s %c", &SA, &PA, &XA, &SB, &PB, &XB);
    int a = strlen(PA), b = strlen(PB);
    int i = 0;
    if(a>b){
        printf("%s\n", SA);
    }else if(a<b){
        printf("%s\n", SB);
    }else{
        while(i<=a){
            if(strcmp(&PA[i], &PB[i])>0){
                printf("%s\n", SA);
                return 0;
            }else if(strcmp(&PA[i], &PB[i])<0){
                printf("%s\n", SB);
                return 0;
            }
            i++;
        }
        printf("-1\n");
    }
    return 0;
}