import java.util.Scanner;

public class Main {
  public static void main(String[] args ) throws Exception {
    Scanner sc = new Scanner(System.in);
    int N = Integer.parseInt(sc.next());
    int N2 = Integer.parseInt(sc.next());
    int N3 = Integer.parseInt(sc.next());
    for(; N2 <= N3; N2++) {
    	if(N2 % N == 0) {
    		System.out.println("OK");
    		break;
    	}

    	if(N2 == N3) {
			System.out.println("NG");
    	}
    }

  }
} import java.util.Scanner; Scanner java.util public class Main {
  public static void main(String[] args ) throws Exception {
    Scanner sc = new Scanner(System.in);
    int N = Integer.parseInt(sc.next());
    int N2 = Integer.parseInt(sc.next());
    int N3 = Integer.parseInt(sc.next());
    for(; N2 <= N3; N2++) {
    	if(N2 % N == 0) {
    		System.out.println("OK");
    		break;
    	}

    	if(N2 == N3) {
			System.out.println("NG");
    	}
    }

  }
} Main public static void main(String[] args ) throws Exception {
    Scanner sc = new Scanner(System.in);
    int N = Integer.parseInt(sc.next());
    int N2 = Integer.parseInt(sc.next());
    int N3 = Integer.parseInt(sc.next());
    for(; N2 <= N3; N2++) {
    	if(N2 % N == 0) {
    		System.out.println("OK");
    		break;
    	}

    	if(N2 == N3) {
			System.out.println("NG");
    	}
    }

  } main {
    Scanner sc = new Scanner(System.in);
    int N = Integer.parseInt(sc.next());
    int N2 = Integer.parseInt(sc.next());
    int N3 = Integer.parseInt(sc.next());
    for(; N2 <= N3; N2++) {
    	if(N2 % N == 0) {
    		System.out.println("OK");
    		break;
    	}

    	if(N2 == N3) {
			System.out.println("NG");
    	}
    }

  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = Integer.parseInt(sc.next()); N Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int N2 = Integer.parseInt(sc.next()); N2 Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int N3 = Integer.parseInt(sc.next()); N3 Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc for(; N2 <= N3; N2++) {
    	if(N2 % N == 0) {
    		System.out.println("OK");
    		break;
    	}

    	if(N2 == N3) {
			System.out.println("NG");
    	}
    } ; N2 <= N3 N2 N3 N2++ N2++ N2 {
    	if(N2 % N == 0) {
    		System.out.println("OK");
    		break;
    	}

    	if(N2 == N3) {
			System.out.println("NG");
    	}
    } {
    	if(N2 % N == 0) {
    		System.out.println("OK");
    		break;
    	}

    	if(N2 == N3) {
			System.out.println("NG");
    	}
    } if(N2 % N == 0) {
    		System.out.println("OK");
    		break;
    	} N2 % N == 0 N2 % N N2 N 0 {
    		System.out.println("OK");
    		break;
    	} System.out.println("OK") System.out.println System.out System System.out "OK" break; if(N2 == N3) {
			System.out.println("NG");
    	} N2 == N3 N2 N3 {
			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 N = Integer.parseInt(sc.next());
    int N2 = Integer.parseInt(sc.next());
    int N3 = Integer.parseInt(sc.next());
    for(; N2 <= N3; N2++) {
    	if(N2 % N == 0) {
    		System.out.println("OK");
    		break;
    	}

    	if(N2 == N3) {
			System.out.println("NG");
    	}
    }

  }
} public class Main {
  public static void main(String[] args ) throws Exception {
    Scanner sc = new Scanner(System.in);
    int N = Integer.parseInt(sc.next());
    int N2 = Integer.parseInt(sc.next());
    int N3 = Integer.parseInt(sc.next());
    for(; N2 <= N3; N2++) {
    	if(N2 % N == 0) {
    		System.out.println("OK");
    		break;
    	}

    	if(N2 == N3) {
			System.out.println("NG");
    	}
    }

  }
} Main
import java.util.Scanner;

public class Main {
  public static void main(String[] args ) throws Exception {
    Scanner sc = new Scanner(System.in);
    int N = Integer.parseInt(sc.next());
    int N2 = Integer.parseInt(sc.next());
    int N3 = Integer.parseInt(sc.next());
    for(; N2 <= N3; N2++) {
    	if(N2 % N == 0) {
    		System.out.println("OK");
    		break;
    	}

    	if(N2 == N3) {
			System.out.println("NG");
    	}
    }

  }
}