#include <iostream>
#include <iomanip>
#include <string>
#include <vector>
#include <cmath>
#include <algorithm>
#include <limits>
#include <sstream>
#include <fstream>
#include <climits>
#include <map>
#include <numeric>
#include <functional>

typedef signed char        int8;
typedef short              int16;
typedef int                int32;
typedef long long          int64;
typedef unsigned char      uint8;
typedef unsigned short     uint16;
typedef unsigned int       uint32;
typedef unsigned long long uint64;

int main(void) {
  int s, w;
  std::cin >> s >> w;
  std::cout << (w >= s ? "unsafe" : "safe") << std::endl;

  return 0;
}
