#include <iostream>
#include <string>
#include <vector>
#include <list>
#include <map>
#include <algorithm>
using namespace std;

typedef unsigned int uint;
typedef unsigned long long ull;
typedef long long ll;
typedef vector<int> vint;
typedef vector<uint> vuint;
typedef vector<ull> vull;
typedef vector<ll> vll;

#define init(type,var) type var;cin>>var;
#define vinit(type,var,n) vector<type> var((uint)n);rep(i,0,n)cin>>var[i];
#define linit(type,var,n) list<type> var;rep(i,0,n){type _v;cin>>_v;var.push_back(_v);}
#define range(container) container.begin(),container.end()
#define rep(i,first,end) for(ull i=(first);i<(end);i++)
#define outl(out) cout<<(out)<<endl;

const ull INF = (ull)(-1LL);

typedef ull ntype;

typedef vector<ntype> vntype;
typedef list<ntype> lntype;

int main(void)
{
	init(ntype, s);
	init(ntype, w);

	outl(w>=s?"unsafe":"safe");

	return 0;
}