#include<bits/stdc++.h>
using namespace std;
#define int long long
int n;
int day;
int t;
int g=1;
signed main() {
	cin >> n;
	t = n;
	while (n >= 7 * g) {
		
		n -= 7 * g;
		g++;
		day += 7;
	}
    if(n>0) {
		day += ceil(n / g * 1.0);
	}
	cout<<day + 1;
	return 0;
}

问下，为啥不加1就不对？