#include <iostream>
#include <cmath>
#include <algorithm>
#include <numeric>
#include <vector>

using lint = long long;

void solve() {
    lint b;
    std::cin >> b;

    int n;
    std::cin >> n;
    std::vector<lint> xs(n);
    for (auto& x : xs) std::cin >> x;
    std::sort(xs.begin(), xs.end());

    auto g = std::min(xs[n / 2],
                      (std::accumulate(xs.begin(), xs.end(), 0LL) + b) / n);

    lint ans = 0;
    for (auto x : xs) {
        ans += std::abs(x - g);
    }
    std::cout << ans << std::endl;
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}