function Main(input) {
    const src = input.split("\n")
    const a = src[0];
    const b = src[1];
    let ans = "NG";
    const regexp = new RegExp(/^(0|[1-9][0-9]*)$/);
    if (regexp.test(a) && regexp.test(b)) ans = "OK";
    console.log(ans);
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));