P2669(金币)

#include <bits/stdc++.h>

using namespace std;

int main() {
    int k, total = 0, i = 1;
    scanf("%d", &k);
    while (k) {
        for (int j = 1; j <= i; j++)
            if (k > 0)
                total += i, k--;
            else {
                printf("%d\n", total);
                return 0;
            }
        i++;
    }
    printf("%d\n", total);
    return 0;
}