#include <cmath>
#include <cstdlib>
#include <iostream>
#include <bitset>
#include <deque>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <vector>
#include <algorithm>
#include <iterator>
#include <string>
#include <chrono>
#include <random>
#include <tuple>
#include <utility>
#include <fstream>
#include <complex>
#define _USE_CMATH_DEFINES

const long INF = (1l << 30);
const long LINF = (1l << 60); //1.15*10^18

long s, w;

int main(){
    scanf("%ld%ld", &s, &w);
    if(s <= w){
        printf("unsafe\n");
    }else{
        printf("safe\n");
    }
}
