'use strict';
const p = s => console.log(s);

function main(input) {
  let s,w = 0;
  [s, w] = input[0].trim().split(" ").map(i => parseInt(i));

  s <= w ? p('unsafe') : p('safe');
}
main(require('fs').readFileSync('/dev/stdin', 'utf8').trim().split("\n"));
