'use strict';

function main(inputs) {
    var sheep = parseInt(inputs.slice(" ")[0])
    var wluf = parseInt(inputs.slice(" ")[1])
    if(sheep > wluf){
        console.log("safe")
    }else {
        console.log("unsafe")
    }
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'));