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

#define max(a,b) (a >= b ? a : b)
#define min(a,b) (a >= b ? b : a)


typedef long long ll;



int main(void){
    int S, W;
    scanf("%d %d", &S, &W);
    if(S<=W){
        printf("unsafe");
    }else{
        printf("safe");
    }


    return 0;
}
