#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#define MAX(a, b) ((a) > (b) ? (a) : (b))

int main(void)
{
long S, W, index;
  
  scanf("%ld %ld", &S, &W);
  if (S > W) {
    printf("safe\n");
  } else {
    printf("unsafe\n");
  }
    
  return 0;
}
