#include <stdio.h>
int main(void){
	int a, b;
	while(1){
		scanf("%d %d", &a, &b);
		if(((1<=a)&&(a<=100))&&((1<=b)&&(b<=100))){
			break;
		}
	}
	if(a<=b){
		printf("unsafe");
	}else{
		printf("safe");
	}
	return 0;
}