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 C (GCC 9.2.1) (judge verdict: Wrong Answer)

#include<stdio.h>

int main (void){
  int A, B, K;
  
  int flag = 0;
  
  scanf("%d",&K);
  scanf("%d %d",&A, &B);
  
  if (K<1 || 1000<K){
    flag = 1;
  }
  
  if( flag == 0 ){
  	if ((A<1) || (A>B) || (1000<B)){
    	flag = 1;
  	}
  }
  
  if( flag == 0){
  	for (int i=1; (i*K)>1000; i++){
    	if(A<=(i*K) && (i*K)<=B){
      		flag = 2;
    	}
  	}
  }
  
  if(flag =! 2){
    printf("NG\n");
  }else{
    printf("OK\n");
  }
  return 0;
}