import java.util.*;

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

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