import java.util.Scanner;

public class Main{
  static public void main(String[] args){
    
    Scanner sc = new Scanner(System.in);
    int K = sc.nextInt();
    int A = sc.nextInt();
    int B = sc.nextInt();
    
    boolean flag = false;
    
    if(K == 1){
      flag = true;
    }else if((A % K) == 0 || (B % K) == 0){
      flag = true;
    }else{
      int mid = (A / K) + 1;
      int midK = K * mid;
      if(A <= midK && midK <= B){
        flag = true;
      }
    }
    
    if(flag){
      System.out.println("OK");
    }else{
      System.out.println("NG");
    }
    
  }
} import java.util.Scanner; Scanner java.util public class Main{
  static public void main(String[] args){
    
    Scanner sc = new Scanner(System.in);
    int K = sc.nextInt();
    int A = sc.nextInt();
    int B = sc.nextInt();
    
    boolean flag = false;
    
    if(K == 1){
      flag = true;
    }else if((A % K) == 0 || (B % K) == 0){
      flag = true;
    }else{
      int mid = (A / K) + 1;
      int midK = K * mid;
      if(A <= midK && midK <= B){
        flag = true;
      }
    }
    
    if(flag){
      System.out.println("OK");
    }else{
      System.out.println("NG");
    }
    
  }
} Main static public void main(String[] args){
    
    Scanner sc = new Scanner(System.in);
    int K = sc.nextInt();
    int A = sc.nextInt();
    int B = sc.nextInt();
    
    boolean flag = false;
    
    if(K == 1){
      flag = true;
    }else if((A % K) == 0 || (B % K) == 0){
      flag = true;
    }else{
      int mid = (A / K) + 1;
      int midK = K * mid;
      if(A <= midK && midK <= B){
        flag = true;
      }
    }
    
    if(flag){
      System.out.println("OK");
    }else{
      System.out.println("NG");
    }
    
  } main {
    
    Scanner sc = new Scanner(System.in);
    int K = sc.nextInt();
    int A = sc.nextInt();
    int B = sc.nextInt();
    
    boolean flag = false;
    
    if(K == 1){
      flag = true;
    }else if((A % K) == 0 || (B % K) == 0){
      flag = true;
    }else{
      int mid = (A / K) + 1;
      int midK = K * mid;
      if(A <= midK && midK <= B){
        flag = true;
      }
    }
    
    if(flag){
      System.out.println("OK");
    }else{
      System.out.println("NG");
    }
    
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int K = sc.nextInt(); K sc.nextInt() sc.nextInt sc int A = sc.nextInt(); A sc.nextInt() sc.nextInt sc int B = sc.nextInt(); B sc.nextInt() sc.nextInt sc boolean flag = false; flag false if(K == 1){
      flag = true;
    }else if((A % K) == 0 || (B % K) == 0){
      flag = true;
    }else{
      int mid = (A / K) + 1;
      int midK = K * mid;
      if(A <= midK && midK <= B){
        flag = true;
      }
    } K == 1 K 1 {
      flag = true;
    } flag = true flag true if((A % K) == 0 || (B % K) == 0){
      flag = true;
    }else{
      int mid = (A / K) + 1;
      int midK = K * mid;
      if(A <= midK && midK <= B){
        flag = true;
      }
    } (A % K) == 0 || (B % K) == 0 (A % K) == 0 (A % K) A K 0 (B % K) == 0 (B % K) B K 0 {
      flag = true;
    } flag = true flag true {
      int mid = (A / K) + 1;
      int midK = K * mid;
      if(A <= midK && midK <= B){
        flag = true;
      }
    } int mid = (A / K) + 1; mid (A / K) + 1 (A / K) A K 1 int midK = K * mid; midK K * mid K mid if(A <= midK && midK <= B){
        flag = true;
      } A <= midK && midK <= B A <= midK A midK midK <= B midK B {
        flag = true;
      } flag = true flag true if(flag){
      System.out.println("OK");
    }else{
      System.out.println("NG");
    } flag {
      System.out.println("OK");
    } System.out.println("OK") System.out.println System.out System System.out "OK" {
      System.out.println("NG");
    } System.out.println("NG") System.out.println System.out System System.out "NG" String[] args args public class Main{
  static public void main(String[] args){
    
    Scanner sc = new Scanner(System.in);
    int K = sc.nextInt();
    int A = sc.nextInt();
    int B = sc.nextInt();
    
    boolean flag = false;
    
    if(K == 1){
      flag = true;
    }else if((A % K) == 0 || (B % K) == 0){
      flag = true;
    }else{
      int mid = (A / K) + 1;
      int midK = K * mid;
      if(A <= midK && midK <= B){
        flag = true;
      }
    }
    
    if(flag){
      System.out.println("OK");
    }else{
      System.out.println("NG");
    }
    
  }
} public class Main{
  static public void main(String[] args){
    
    Scanner sc = new Scanner(System.in);
    int K = sc.nextInt();
    int A = sc.nextInt();
    int B = sc.nextInt();
    
    boolean flag = false;
    
    if(K == 1){
      flag = true;
    }else if((A % K) == 0 || (B % K) == 0){
      flag = true;
    }else{
      int mid = (A / K) + 1;
      int midK = K * mid;
      if(A <= midK && midK <= B){
        flag = true;
      }
    }
    
    if(flag){
      System.out.println("OK");
    }else{
      System.out.println("NG");
    }
    
  }
} Main
import java.util.Scanner;

public class Main{
  static public void main(String[] args){
    
    Scanner sc = new Scanner(System.in);
    int K = sc.nextInt();
    int A = sc.nextInt();
    int B = sc.nextInt();
    
    boolean flag = false;
    
    if(K == 1){
      flag = true;
    }else if((A % K) == 0 || (B % K) == 0){
      flag = true;
    }else{
      int mid = (A / K) + 1;
      int midK = K * mid;
      if(A <= midK && midK <= B){
        flag = true;
      }
    }
    
    if(flag){
      System.out.println("OK");
    }else{
      System.out.println("NG");
    }
    
  }
}