#include<bits/stdc++.h>
#define int unsigned long long
using namespace std;
int n,ans;
signed main(){
	cin>>n;
	int l=1,r=300000000;
	while(l>=r){
		int mid=(l+r)/2;
		int week=mid/7,day=mid%7;
		int jb=(7*(1+week)*week/2);
		jb+=(week+1)*day;
		if(jb>=n){
			r=mid-1;
			ans=mid;
		}else{
			l=mid+1;
		}
	}
	cout<<ans;
	return 0;
}

为什么样例过不了，看着没错啊