function Main(k, a, b) {
    let result = 'NG';

    for (let i = 1; k * i <= 1000; i += 1) {
        if (a <= (k * i) && (k * i) <= b) {
            result = 'OK';
            break;
        }
    }  
}

Main(require("fs").readFileSync("/dev/stdin", "utf8"));