#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#define Rep(i,a,n)for(int i=(int)(a);i<(int)(n);i++)
#define rep(i,n)Rep(i,0,n)
typedef long long ll;
typedef long double ld;
#define M(x,y) ((x)>(y)?(x):(y))
#define m(x,y) ((x)<(y)?(x):(y))

int main() {
	int a, b;
	scanf("%d %d", &a, &b);
	if (a > b)printf("safe");
	else printf("unsafe");
}