Problem:
Score: 100 points

Problem Statement

Takahashi the Jumbo will practice golf.

His objective is to get a carry distance that is a multiple of K, while he can only make a carry distance of between A and B (inclusive).

If he can achieve the objective, print OK; if he cannot, print NG.

Constraints

All values in input are integers.

1 \leq A \leq B \leq 1000

1 \leq K \leq 1000

Input

Input is given from Standard Input in the following format:

K
A B

Output

If he can achieve the objective, print OK; if he cannot, print NG.

Sample Input 1

7
500 600

Sample Output 1

OK

Among the multiples of 7, for example, 567 lies between 500 and 600.

Sample Input 2

4
5 7

Sample Output 2

NG

No multiple of 4 lies between 5 and 7.

Sample Input 3

1
11 11

Sample Output 3

OK

Solution in JavaScript (Node.js 12.16.1) (judge verdict: Accepted)

'use strict';

const inputs = require('fs').readFileSync('/dev/stdin', 'utf8').split('\n');

const k = parseInt(inputs[0], 10);
const ab = inputs[1].split(' ').map(v => parseInt(v, 10));

if (k === 1) {
  console.log('OK');
  return;
}

if (k === ab[0]) {
  console.log('OK');
  return;
}

let c = Math.floor(ab[0] / k);
if (c === 0) {
  c = 1
}

for (;;) {
  if (c * k < ab[0]) {
    ++c;

    continue;
  }

  if (c * k > ab[1]) {
    break;
  }

  if (c * k % k === 0) {
    console.log('OK');
    return;
  }

  ++c;

  if (c * k > ab[1]) {
    break;
  }
}

console.log('NG');