题解

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

int main(){
    int n = 1 , k , ans = 0;
    cin >> k;
    while (k > 0){
        for (int i = 1 ; i <= n ; i++){
            if (k == 0){
                break;
            }
            k--;
            ans += n;
        }
        n++;
    }
    cout << ans;
    return 0;
}