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

#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define MIN(a, b) ((a) < (b) ? (a) : (b))

int main(void){
    int s, w;
    scanf("%d%d",&s ,&w);
    if(w>=s){
        printf("unsafe");
    }
    else{
        printf("safe");
    }
    return 0; 
}
