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

char SA[101];
char SB[101];

char PA[10001];
char PB[10001];

int main(void) {
  int order;

  scanf("%s %s %*s %s %s %*s", SA, PA, SB, PB);
  order = strcmp(PA, PB);
  printf("%s\n", order > 0 ? SA : order < 0 ? SB : "-1");

  return 0;
}