function main(input) {
    let N = 0 | input.split("\n");
    return  N >= 30 ? "Yes": "No";
}

//******************************
exports.main = main;

function Main(input) {
    console.log(main(input));
}

if (process.argv[2] !== "test") {
    Main(require("fs").readFileSync("/dev/stdin", "utf8"));
}
