#include <stdio.h>

int main()
{
    int s;
    int w;

    do{
        scanf("%d", &s);

    }while(s<0 || s>100);

    do{
        scanf("%d", &w);

    }while(w<0 || w>100);

    if(w>=s){
        printf("%s\n", "unsafe");
    } else {
    printf("%s\n", "safe");
    }

    return 0;
}
