#include<bits/stdc++.h>
#define int long long
#define rep(i,n) for(int i=0;i<n;i++)
#define srep(i,n,m) for(int i=n;i<m;i++)
#define elif else if
#define INF 1000000007
using namespace std;
int gcd(int a,int b){
    if(b==0) return a;
    return gcd(b,a%b);
}
int n,m,cnt=0,o,aa[220000],cntl=0,ab[220000];
pair<int,int> p[220000];
string s,ss[220000];
char c,cc[5000][5000]={};
queue<int> que;
signed main(){
    cin>>n>>m;
    if(n>m){
        cout<<"safe"<<endl;
    }else{
        cout<<"unsafe"<<endl;
    }
}