#include <iostream>
#include <cstdio>
#include <string>
#include <algorithm>
#include <cstring>
#include <vector>
#include <queue>
#include <map>
#include <set>
#include <bitset>
#include <stack>
#include <cmath>
#include <time.h>
#include <unordered_set>
#include <unordered_map>
#define ll long long
#define LINF 0x3f3f3f3f3f3f3f3f
#define INF 0x3f3f3f3f
#define PI 3.14159265
#define RAND (rand()*rand())
#define MAX(x, y) ((x) > (y) ? (x):(y)) 
#define MIN(x, y) ((x) > (y) ? (y):(x))
#define ABS(x) ((x) > 0 ? (x) : -(x))
#define CEIL(x, y) (((x) + (y) - 1)/(y))
using namespace std;
const int MAXN = 1e5 + 5;
const ll MOD = 1e9 + 7;
const double eps = 1e-7;
int N, M, K, Q, T;

int main()
{
	int i, j, a, b;
	scanf("%d%d", &a, &b);
	if (a <= b) {
		printf("unsafe");
	}
	else printf("safe");
	return 0;
}