【加急】样例通过了，但是60分

#include<bits/stdc++.h>
using namespace std;

int main() {
	int n;
	cin >> n;
	int l = 0, r = n;
	int ans = 999;
	while (l <= r) {
		int mid = l+(r-l)/2;
		int t = 0;
		if (mid % 2 == 0) {
			t = mid / 2 * 3;
		}
		else {
			t = mid / 2 * 3 + 1;
		}
		if(t>=n){
			r = mid - 1;
			ans = mid;
		}
		else {
			l = mid + 1;
		}
	}
	printf("%d\n", ans);
	return 0;
}