Submission

Score: 100

User: Few500

Problemset: โชว์ของโลมา

Language: cpp

Time: 0.002 second

Submitted On: 2026-03-21 20:35:54

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int n;
    cin >> n;
    if(n == 1){
        cout << "1\n";
        return 0;
    }
    long long total = (n * 3 - 2) % 10;
    long long prev = n * 3 - 2;
    for(int i=2; i<n; i++){
        if(i % 2 == 0)
            prev++;
        else
            prev += (n-i+1) * 4 - 3;
        total += prev % 10;
    }
    if(n % 2 == 0)
        total += (prev - 1) % 10;
    else
        total += (prev + 1) % 10;
    cout << total << '\n';
    return 0;
}