import java.util.*;

public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 998244353;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	int len = (int)1e6 + 1;
	
	
	void doIt() {
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();
		int len = K;
		while(len <= B) {
			if(A <= len) {
				System.out.println("OK");
				return;
			}
			
			len += K;
		}
		System.out.println("NG");
	}
	
	
	public static void main(String[] args) {
		new Main().doIt();
	}

} import java.util.*; util.* java public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 998244353;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	int len = (int)1e6 + 1;
	
	
	void doIt() {
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();
		int len = K;
		while(len <= B) {
			if(A <= len) {
				System.out.println("OK");
				return;
			}
			
			len += K;
		}
		System.out.println("NG");
	}
	
	
	public static void main(String[] args) {
		new Main().doIt();
	}

} Main Scanner sc = new Scanner(System.in); sc new Scanner(System.in) final int MOD = 998244353; MOD 998244353 final int MAX = Integer.MAX_VALUE; MAX Integer.MAX_VALUE Integer Integer.MAX_VALUE final long LMAX = Long.MAX_VALUE; LMAX Long.MAX_VALUE Long Long.MAX_VALUE int len = (int)1e6 + 1; len (int)1e6 + 1 (int)1e6 1 void doIt() {
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();
		int len = K;
		while(len <= B) {
			if(A <= len) {
				System.out.println("OK");
				return;
			}
			
			len += K;
		}
		System.out.println("NG");
	} doIt {
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();
		int len = K;
		while(len <= B) {
			if(A <= len) {
				System.out.println("OK");
				return;
			}
			
			len += K;
		}
		System.out.println("NG");
	} 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 len = K; len K while(len <= B) {
			if(A <= len) {
				System.out.println("OK");
				return;
			}
			
			len += K;
		} len <= B len B {
			if(A <= len) {
				System.out.println("OK");
				return;
			}
			
			len += K;
		} if(A <= len) {
				System.out.println("OK");
				return;
			} A <= len A len {
				System.out.println("OK");
				return;
			} System.out.println("OK") System.out.println System.out System System.out "OK" return; len += K len K System.out.println("NG") System.out.println System.out System System.out "NG" public static void main(String[] args) {
		new Main().doIt();
	} main {
		new Main().doIt();
	} new Main().doIt() new Main().doIt new Main() String[] args args public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 998244353;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	int len = (int)1e6 + 1;
	
	
	void doIt() {
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();
		int len = K;
		while(len <= B) {
			if(A <= len) {
				System.out.println("OK");
				return;
			}
			
			len += K;
		}
		System.out.println("NG");
	}
	
	
	public static void main(String[] args) {
		new Main().doIt();
	}

} public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 998244353;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	int len = (int)1e6 + 1;
	
	
	void doIt() {
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();
		int len = K;
		while(len <= B) {
			if(A <= len) {
				System.out.println("OK");
				return;
			}
			
			len += K;
		}
		System.out.println("NG");
	}
	
	
	public static void main(String[] args) {
		new Main().doIt();
	}

} Main
import java.util.*;

public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 998244353;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	int len = (int)1e6 + 1;
	
	
	void doIt() {
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();
		int len = K;
		while(len <= B) {
			if(A <= len) {
				System.out.println("OK");
				return;
			}
			
			len += K;
		}
		System.out.println("NG");
	}
	
	
	public static void main(String[] args) {
		new Main().doIt();
	}

}
