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 <iostream>
#include <string>
#include <sstream>

using namespace std;

stringstream split_str(string istr, string c , int &count){
    string str(istr), separator(c);
    string tstr = str + separator;
    stringstream ss;
    long l = tstr.length(), sl = separator.length();
    string::size_type pos = 0, prev = 0; count = 0;
    for (;pos < l && (pos = tstr.find(separator, pos)) != string::npos; prev = (pos += sl)) {
        string item = tstr.substr(prev, pos - prev);
        if(item.length() > 0 ){ 
            (count==0) ? (ss << item) : (ss << " " << item);
            count++;
         }
            
    }
    return ss;
}

int main(){
    int K,A,B,t;
    string line1,line2,K_string,A_string,B_string;
    stringstream ss;
    getline(cin,line1);
    getline(cin,line2);

    ss = split_str(line1, " ", t);
    ss >> K_string;
    K = stoi(K_string);
    
    ss = split_str(line2, " ", t);
    ss >> A_string;
    ss >> B_string;
    A = stoi(A_string);
    B = stoi(B_string);
    
    if(K <= 1000 && K>=1 && 1 <= A && B >= 1000 && A <= B){
    if(K == 1){
        cout << "OK";
    }else{
        (A + K - (A%K) ) > B ? cout << "NG" : cout << "OK";
    }
    }else{
        cout << "NG";
    }
    
    return 0;
}