Submission

Score: 100

User: august

Problemset: โชว์ของโลมา

Language: cpp

Time: 0.003 second

Submitted On: 2026-03-11 12:24:35

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

int32_t main() {
    cin.tie(0)->sync_with_stdio(0);
    int n;
    cin>> n;

    if (n==1) {
        cout<< 1;
        return 0;
    }
   
    int cur=2*n, add=2*n-4;

    int ans = 0;
    for (int i=2; i<=n; i++) {
        //cout<< cur<< ' ';
        if (i%2==0) ans += (cur+n-i)%10;
        else ans += (cur-n+i)%10;

        if (i==n) {
            if (n%2==0 )ans += (cur-1)%10; 
            else ans += (cur+1)%10;
        }
        cur += add;
        if (i%2 == 1) add-=4;
    }
    cout<< ans;
}