Submission

Score: 100

User: Ninstroyer

Problemset: โชว์ของโลมา

Language: cpp

Time: 0.003 second

Submitted On: 2026-03-08 17:07:51

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

ll n;

int main()
{
	ios::sync_with_stdio(false); cin.tie(0);
	cin>>n;
	ll res = 0;
	if(n==1) return cout<<1,0;
	if(n<1) return cout<<0,0;
	ll add = n+(n-2);
	ll cur = n+1;
	bool bot = false;
	while(add>2)
	{
		if(bot)
		{
			res += cur-(cur/10)*10;
			cur += add;
			bot = false;
		}
		else
		{
			cur += add-1;
			res += cur-(cur/10)*10;
			cur++;
			bot = true;
		}
		add -= 2;
	}
	n *= n;
	res += n-(n/10)*10;
	n -= 1;
	res += n-(n/10)*10;
	cout<<res;
}