#include <stdio.h>
#define SIZE 2
void compare(int a[SIZE]){
  if(a[0]<=a[1]){
    printf("unsafe\n");
  }
  else{
    printf("safe\n");
  }
}

int main(void){
  int num[SIZE];
  scanf("%d %d", &num[0], &num[1]);
  compare(num);
  return 0 ;
}
