/*
 * FileName:     A
 * CreatedDate:  2020-04-26 20:59:52 +0900
 * LastModified: 2020-04-26 21:01:25 +0900
 */

#include <stdio.h>

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