import java.util.Scanner;

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

		
	}

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

		
	}

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

		
	} main {
		Scanner s = new Scanner(System.in);
		int K = s.nextInt();
		int A = s.nextInt();
		int B = s.nextInt();
		
		boolean ans = false;
		for(int i=A; i<=B; i++) {
			if(i%K == 0) {
				ans = true;
				break;
			}
		}
		
		if(ans) {System.out.println("OK");}
		else {System.out.println("NG");}

		
	} Scanner s = new Scanner(System.in); s new Scanner(System.in) int K = s.nextInt(); K s.nextInt() s.nextInt s int A = s.nextInt(); A s.nextInt() s.nextInt s int B = s.nextInt(); B s.nextInt() s.nextInt s boolean ans = false; ans false for(int i=A; i<=B; i++) {
			if(i%K == 0) {
				ans = true;
				break;
			}
		} int i=A; int i=A; i A i<=B i B i++ i++ i {
			if(i%K == 0) {
				ans = true;
				break;
			}
		} {
			if(i%K == 0) {
				ans = true;
				break;
			}
		} if(i%K == 0) {
				ans = true;
				break;
			} i%K == 0 i%K i K 0 {
				ans = true;
				break;
			} ans = true ans true break; if(ans) {System.out.println("OK");}
		else {System.out.println("NG");} ans {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 s = new Scanner(System.in);
		int K = s.nextInt();
		int A = s.nextInt();
		int B = s.nextInt();
		
		boolean ans = false;
		for(int i=A; i<=B; i++) {
			if(i%K == 0) {
				ans = true;
				break;
			}
		}
		
		if(ans) {System.out.println("OK");}
		else {System.out.println("NG");}

		
	}

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

		
	}

} Main
import java.util.Scanner;

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

		
	}

}
