#include <bits/stdc++.h>
#define ll long long int
#define mod 1000000007
#define intpair pair<int,int>
using namespace std;
inline int add(int a,int b){a+=b;if(a>=mod)a-=mod;return a;}
inline int mul(int a,int b){return (a*1ll*b)%mod;}
inline int pow(int a,int b){int rt=1;while(b>0){if(b&1)rt=mul(rt,a);a=mul(a,a);b>>=1;}return rt;}
inline bool sortinrev(const pair<int,int> &a,const pair<int,int> &b){return (a.first > b.first);} //sort pair in descending order
int main(){
		ios_base::sync_with_stdio(false);
    cin.tie(NULL);
		ll w,s;
		cin>>s>>w;
		if(w>=s)cout<<"unsafe\n";
		else cout<<"safe\n";
}

