#include<stdio.h>
int main() 
{
  int S, W;
  scanf("%d", &S) ;
  scanf("%d", &W) ;
  if((S>=1||S<=100) &&(W>=1||W<=100)) 
  {
    if(S<=W) 
    {printf("unsafe") ;}
    else
    {printf("safe") ;}
  }
}