const Main = () => {
    const line = require('fs').readFileSync('/dev/stdin', 'utf8');
    const [SS, WW] = line.split(' ');
    const S = parseInt(SS, 10);
    const W = parseInt(WW, 10);
    if (S <= W) {
        console.log('unsafe');
    } else {
        console.log('safe');
    }
}

Main();
