process.stdin.resume();
process.stdin.setEncoding('utf8');

var lines = []
var reader = require('readline').createInterface({
  input: process.stdin,
  output: process.stdout
});

reader.on('line', (line) => {
  lines.push(line);
});

reader.on('close', () => {
 var sandw = lines[0].split(' ');
 var s = Number(sandw[0]);
 var w = Number(sandw[1]);

 if(s <= w){
   console.log("unsafe");
 }else{
   console.log("safe");
 }

 
});