#include <bits/stdc++.h>
#include<vector>
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
#define MAX 400000
#define BEGIN 1
#define DEFAULT_VALUE 0
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> new_data_set;
new_data_set s[MAX];
int main()
{
    int S,W;
    scanf("%d %d",&S,&W);
    if(W>=S)
    {
        printf("unsafe");
    }
    else
    {
        printf("safe");
    }
    return 0;
}
