#include <iostream>
#include <iostream>
#include <string.h>
#include <vector>
#include <queue>
#include <cstdio>
#include <math.h>
#include <map>
#include <algorithm>
#include <deque>
#include <stack>
#include<set>
//#include <bits/stdc++.h>
#define lson l,mid,rt<<1

#define rson mid+1,r,rt<<1|1

const int N=1e5+100;
using namespace std;

typedef long long ll;
const int inf=0x3f3f3f3f;
const int mod=1e9+7;

int main()
{
    int n,m;
    cin>>n>>m;
    string s;
    s=n<=m?"unsafe":"safe";
    cout<<s;
    return 0;
}
