#include <iostream>
#include <algorithm>
#include <string>
#include <stdlib.h>
#include <vector>
#include <climits>
#include <math.h>
#include <map>
#include <set>
#include <stack>
#include <iomanip>
using namespace std; 
#define Endl '\n'
int main()
{
    int a,b;
    cin>>a>>b;
    if (a>b)
    {
        cout<<"safe";
    }
    else
        cout<<"unsafe";
}