import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
		int arg = 0;
        String ans = "NG";

        for (int i = 0; i <= 1000; i++) {
		arg = K*i;
            if (A <= arg && arg <= B) {
                ans = "OK";
				break;
            } else if (B < arg) {
				break;
			}
        }

        System.out.println(ans);

        sc.close();
    }    
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
		int arg = 0;
        String ans = "NG";

        for (int i = 0; i <= 1000; i++) {
		arg = K*i;
            if (A <= arg && arg <= B) {
                ans = "OK";
				break;
            } else if (B < arg) {
				break;
			}
        }

        System.out.println(ans);

        sc.close();
    }    
} Main public static void main(String[] args) throws Exception {
        
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
		int arg = 0;
        String ans = "NG";

        for (int i = 0; i <= 1000; i++) {
		arg = K*i;
            if (A <= arg && arg <= B) {
                ans = "OK";
				break;
            } else if (B < arg) {
				break;
			}
        }

        System.out.println(ans);

        sc.close();
    } main {
        
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
		int arg = 0;
        String ans = "NG";

        for (int i = 0; i <= 1000; i++) {
		arg = K*i;
            if (A <= arg && arg <= B) {
                ans = "OK";
				break;
            } else if (B < arg) {
				break;
			}
        }

        System.out.println(ans);

        sc.close();
    } 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 arg = 0; arg 0 String ans = "NG"; ans "NG" for (int i = 0; i <= 1000; i++) {
		arg = K*i;
            if (A <= arg && arg <= B) {
                ans = "OK";
				break;
            } else if (B < arg) {
				break;
			}
        } int i = 0; int i = 0; i 0 i <= 1000 i 1000 i++ i++ i {
		arg = K*i;
            if (A <= arg && arg <= B) {
                ans = "OK";
				break;
            } else if (B < arg) {
				break;
			}
        } {
		arg = K*i;
            if (A <= arg && arg <= B) {
                ans = "OK";
				break;
            } else if (B < arg) {
				break;
			}
        } arg = K*i arg K*i K i if (A <= arg && arg <= B) {
                ans = "OK";
				break;
            } else if (B < arg) {
				break;
			} A <= arg && arg <= B A <= arg A arg arg <= B arg B {
                ans = "OK";
				break;
            } ans = "OK" ans "OK" break; if (B < arg) {
				break;
			} B < arg B arg {
				break;
			} break; System.out.println(ans) System.out.println System.out System System.out ans sc.close() sc.close sc String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
		int arg = 0;
        String ans = "NG";

        for (int i = 0; i <= 1000; i++) {
		arg = K*i;
            if (A <= arg && arg <= B) {
                ans = "OK";
				break;
            } else if (B < arg) {
				break;
			}
        }

        System.out.println(ans);

        sc.close();
    }    
} public class Main {
    public static void main(String[] args) throws Exception {
        
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
		int arg = 0;
        String ans = "NG";

        for (int i = 0; i <= 1000; i++) {
		arg = K*i;
            if (A <= arg && arg <= B) {
                ans = "OK";
				break;
            } else if (B < arg) {
				break;
			}
        }

        System.out.println(ans);

        sc.close();
    }    
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
		int arg = 0;
        String ans = "NG";

        for (int i = 0; i <= 1000; i++) {
		arg = K*i;
            if (A <= arg && arg <= B) {
                ans = "OK";
				break;
            } else if (B < arg) {
				break;
			}
        }

        System.out.println(ans);

        sc.close();
    }    
}
