#include<iostream>
#include<algorithm>
#include<bits/stdc++.h>
using namespace std;
//#define mp make_pair
#define pb push_back
#define int long long
#define pi 3.141592653589793238462643383279502
#define M 1000000007
#define F first
#define S second
#define pii pair<int,int>
#define rep(i,n) for(int i=0;i<n;i++)
bool isPowerOfTwo(int n)
{
   if(n==0)
   return false;

   return (ceil(log2(n)) == floor(log2(n)));
}
int power(int x, unsigned int y)
{
    int res = 1;

    x = x;
    while (y > 0)
    {
        if (y & 1)
            res = (res*x);

        y = y>>1;
        x = (x*x);
    }
    return res;
}
bool isprime(int x)
{
      if(x<2)
        return false;
    for(int i=2;i*i<=x;i++)
     {
        if (x%i==0)
            return false;
    }
    return true;
}
vector<int>primeFactors(int n)
{
    vector<int>v;
    while (n % 2 == 0)
    {
        v.pb(2);
        n = n/2;
    }
    for (int i = 3; i <= sqrt(n); i = i + 2)
    {
        while (n % i == 0)
        {
            v.pb(i);
            n = n/i;
        }
    }
    if (n > 2)
        v.pb(n);
    return v;
}

void solve()
{
int s,w;
cin>>s>>w;
if(w>=s)
    cout<<"unsafe"<<endl;
else
    cout<<"safe"<<endl;
}

signed main()
{ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
int t;
//cin>>t;
t=1;
while(t--)
{
  solve();
}
}
