import java.util.*;
import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		while(a<=b) {
			if(a%k == 0) {
				System.out.println("OK");
				System.exit(0);
			}else {
				a += 1;
			}
		}
		
		System.out.println("NG");
		
	}	
	
	
	//最小公約数
	/*
	static int gcd (int a, int b) {
		int temp;
		while((temp = a%b)!=0) {
			a = b;
			b = temp;
		}
		return b;
	}
	*/
	
} import java.util.*; util.* java import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		while(a<=b) {
			if(a%k == 0) {
				System.out.println("OK");
				System.exit(0);
			}else {
				a += 1;
			}
		}
		
		System.out.println("NG");
		
	}	
	
	
	//最小公約数
	/*
	static int gcd (int a, int b) {
		int temp;
		while((temp = a%b)!=0) {
			a = b;
			b = temp;
		}
		return b;
	}
	*/
	
} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		while(a<=b) {
			if(a%k == 0) {
				System.out.println("OK");
				System.exit(0);
			}else {
				a += 1;
			}
		}
		
		System.out.println("NG");
		
	} main {
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		while(a<=b) {
			if(a%k == 0) {
				System.out.println("OK");
				System.exit(0);
			}else {
				a += 1;
			}
		}
		
		System.out.println("NG");
		
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int k = scan.nextInt(); k scan.nextInt() scan.nextInt scan int a = scan.nextInt(); a scan.nextInt() scan.nextInt scan int b = scan.nextInt(); b scan.nextInt() scan.nextInt scan while(a<=b) {
			if(a%k == 0) {
				System.out.println("OK");
				System.exit(0);
			}else {
				a += 1;
			}
		} a<=b a b {
			if(a%k == 0) {
				System.out.println("OK");
				System.exit(0);
			}else {
				a += 1;
			}
		} if(a%k == 0) {
				System.out.println("OK");
				System.exit(0);
			}else {
				a += 1;
			} a%k == 0 a%k a k 0 {
				System.out.println("OK");
				System.exit(0);
			} System.out.println("OK") System.out.println System.out System System.out "OK" System.exit(0) System.exit System 0 {
				a += 1;
			} a += 1 a 1 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 scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		while(a<=b) {
			if(a%k == 0) {
				System.out.println("OK");
				System.exit(0);
			}else {
				a += 1;
			}
		}
		
		System.out.println("NG");
		
	}	
	
	
	//最小公約数
	/*
	static int gcd (int a, int b) {
		int temp;
		while((temp = a%b)!=0) {
			a = b;
			b = temp;
		}
		return b;
	}
	*/
	
} public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		while(a<=b) {
			if(a%k == 0) {
				System.out.println("OK");
				System.exit(0);
			}else {
				a += 1;
			}
		}
		
		System.out.println("NG");
		
	}	
	
	
	//最小公約数
	/*
	static int gcd (int a, int b) {
		int temp;
		while((temp = a%b)!=0) {
			a = b;
			b = temp;
		}
		return b;
	}
	*/
	
} Main
import java.util.*;
import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		while(a<=b) {
			if(a%k == 0) {
				System.out.println("OK");
				System.exit(0);
			}else {
				a += 1;
			}
		}
		
		System.out.println("NG");
		
	}	
	
	
	//最小公約数
	/*
	static int gcd (int a, int b) {
		int temp;
		while((temp = a%b)!=0) {
			a = b;
			b = temp;
		}
		return b;
	}
	*/
	
}