#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;++i)
#define rrep(i,n) for(int i=n-1;i>=0;--i)
#define REP(i,a,b) for(int i=a;i<b;i++)
#define yesno(flg) if(flg){cout<<"YES"<<endl;}else{cout<<"NO"<<endl;}
#define vi vector<int>
#define pb push_back
#define i197 1000000007
#define MAX_N 200002
using namespace std;

typedef long long ll;
typedef pair<int,int> Pii;
typedef pair<Pii,int> Piii;
const int inf=1000000000;
struct edge{
	int myc,to,c,cost;
};
struct pos{
	int to,cost,color;
};
int dy[]={0, 0, 1, -1};
int dx[]={1, -1, 0, 0};
int f[MAX_N]={};
int b[MAX_N]={};
bool dp[MAX_N]={};

int main() {
	int s,w;
    cin>>s>>w;
    if(s>w){
        cout<<"safe"<<endl;
    }else{
        cout<<"unsafe"<<endl;
    }
	return 0;
}
