public static void CC18_4_brute_force(int n) {//PASS
		if (n <= 0) {
			System.out.println ("Wrong number");
			return;
		}
		else {
			int sum=0;
			for (int i=1; i<=n; ++i) {
				int sum_temp = 0;
				int iter = i;
				while(iter != 0) {
					if ((iter%10) == 2) sum_temp++;
					iter = iter/10;
				}
				sum += sum_temp;
			}
			System.out.println ("The number of 2s is: " + sum);
		}
	}