#include <stdio.h>
int main() {
	int luachon;
	do {
		printf("1. In ra man hinh tu hello.\n");
		printf("2. In ra man hinh vong lap for\n");
		printf("3. In ra man hinh vong lap while\n");
		printf("4. Thoat chuong trinh\n");
		printf("Ban chon chuc nang nao: ");
		scanf_s("%d", &luachon);
		switch (luachon) {
			case 1: printf("HELLO"); break;
			case 2: printf("Vong lap FOR"); break;
			case 3: printf("Vong lap while"); break;
			case 4: printf("Thoat chuong trinh"); break;
		}
	} while (luachon > 4 || luachon < 1);
	return 0;
}