#include <bits/stdc++.h>

using namespace std;

const int N=1e6+3;

const double eps=1e-9;

#define pb push_back
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()
#define f first
#define s second
typedef long long ll;

const int dx[]={1,-1,0,0},
		  dy[]={0,0,1,-1};

const int mod=1e9+7;

int n,a[N],b[N],m,k,q,u,v,x,y,tc,l,r,c,ans;

char s[N],grid[N];

void IO(){
	ios::sync_with_stdio(false);
	cin.tie(0);cout.tie(0);
	#ifndef ONLINE_JUDGE
		freopen("test.txt","r",stdin);
	#endif
}

int main(){
	//IO();
	scanf("%d%d",&n,&m);
	if (n<=m)
		printf("un");
	printf("safe\n");
}
