#include<stdio.h>
#include<stdlib.h>
int max(int a,int b){return a>b?a:b;}
int min(int a,int b){return a<b?a:b;} 
int main(void)
{
  int a,b;
    scanf("%d %d",&a,&b);
  if(a>b)
    printf("safe");
  else
    printf("unsafe");
}