function main(k, l, r) {
  	let quo1=Math.floor(l/k);
 	let quo2=Math.floor(r/k);
 	let rem=l%k;
 	
  	if(rem==0)
 	{
   		count=quo2-quo1+1;
 	}
 	else
 	{
    	count=quo2-quo1;
  	}

  	if(count === 0) {
    	console.log("NG");
    } else {
    	console.log("OK");
    }
}
const input = require('fs').readFileSync('/dev/stdin', 'utf8').split('\n');
const [l , r] = input[1].split(" ").map(x=> parseInt(x));

main(parseInt(input[0]), l , r);
