import java.util.*;

public class Main {
    public static void main(String[] args ) throws Exception {
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
		boolean flag = false;
      	int times = (B-A);
        for(int i=0;i<times+1;i++){
            if(A % K == 0){
                System.out.println("OK");
              flag = true;
                break;
            } else if(A < B){
                A++;
            }
        }
      if(!flag){
        System.out.println("NG");
      }
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args ) throws Exception {
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
		boolean flag = false;
      	int times = (B-A);
        for(int i=0;i<times+1;i++){
            if(A % K == 0){
                System.out.println("OK");
              flag = true;
                break;
            } else if(A < B){
                A++;
            }
        }
      if(!flag){
        System.out.println("NG");
      }
    }
} Main public static void main(String[] args ) throws Exception {
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
		boolean flag = false;
      	int times = (B-A);
        for(int i=0;i<times+1;i++){
            if(A % K == 0){
                System.out.println("OK");
              flag = true;
                break;
            } else if(A < B){
                A++;
            }
        }
      if(!flag){
        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;
      	int times = (B-A);
        for(int i=0;i<times+1;i++){
            if(A % K == 0){
                System.out.println("OK");
              flag = true;
                break;
            } else if(A < B){
                A++;
            }
        }
      if(!flag){
        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 int times = (B-A); times (B-A) B A for(int i=0;i<times+1;i++){
            if(A % K == 0){
                System.out.println("OK");
              flag = true;
                break;
            } else if(A < B){
                A++;
            }
        } int i=0; int i=0; i 0 i<times+1 i times+1 times 1 i++ i++ i {
            if(A % K == 0){
                System.out.println("OK");
              flag = true;
                break;
            } else if(A < B){
                A++;
            }
        } {
            if(A % K == 0){
                System.out.println("OK");
              flag = true;
                break;
            } else if(A < B){
                A++;
            }
        } if(A % K == 0){
                System.out.println("OK");
              flag = true;
                break;
            } else if(A < B){
                A++;
            } A % K == 0 A % K A K 0 {
                System.out.println("OK");
              flag = true;
                break;
            } System.out.println("OK") System.out.println System.out System System.out "OK" flag = true flag true break; if(A < B){
                A++;
            } A < B A B {
                A++;
            } A++ A if(!flag){
        System.out.println("NG");
      } !flag flag {
        System.out.println("NG");
      } System.out.println("NG") System.out.println System.out System System.out "NG" String[] args args public class Main {
    public static void main(String[] args ) throws Exception {
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
		boolean flag = false;
      	int times = (B-A);
        for(int i=0;i<times+1;i++){
            if(A % K == 0){
                System.out.println("OK");
              flag = true;
                break;
            } else if(A < B){
                A++;
            }
        }
      if(!flag){
        System.out.println("NG");
      }
    }
} public class Main {
    public static void main(String[] args ) throws Exception {
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
		boolean flag = false;
      	int times = (B-A);
        for(int i=0;i<times+1;i++){
            if(A % K == 0){
                System.out.println("OK");
              flag = true;
                break;
            } else if(A < B){
                A++;
            }
        }
      if(!flag){
        System.out.println("NG");
      }
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args ) throws Exception {
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
		boolean flag = false;
      	int times = (B-A);
        for(int i=0;i<times+1;i++){
            if(A % K == 0){
                System.out.println("OK");
              flag = true;
                break;
            } else if(A < B){
                A++;
            }
        }
      if(!flag){
        System.out.println("NG");
      }
    }
}
