#include<bits/stdc++.h>
using namespace std ;
typedef long long int ll ;
long long int power(long long int a,long long int n,long long int m) ;
 long long int power(long long int a,long long int n,long long int m)
{  if(n==0)
   return 1 ;
   long long int x=power(a,n/2,m) ;
   if(n%2!=0)
    return (((a*x)%m)*(x)%m)%m ;
    else return (x*x)%m ;
}



int main()
{ long long int n,i,j,x,y,m,k,t,sum,count,cnt,b,c,d,j1,z,a,o;
   cin>>x>>y ;
   if(y>=x)
    cout<<"unsafe" ;
   else cout<<"safe" ;
   return 0 }
