百钱买百鸡题解

#include <bits/stdc++.h>
using namespace std;
int n,cnt = 0;
int main(){
	cin >> n;
	for(int i = 0;i <= n / 7;i ++){
		int j = (n - 7 * i) / 4;
		if((n - 7 * i) % 4 == 0 && (n - i - j) % 3 == 0) cnt++;
	}
	cout << cnt << endl;
	return 0;
}