#include <iostream>
#include <limits>
#include <vector>

using i64 = long long;

static constexpr i64 inf = std::numeric_limits<i64>::max() / 2;

i64 iabs(i64 x)
{
    return x > 0 ? x : -x;
}

int main()
{
    i64 b;
    std::cin >> b;
    int n;
    std::cin >> n;
    std::vector<i64> c(n);
    for (auto &e : c)
        std::cin >> e;

    const auto f = [&](i64 t) {
        i64 ret = 0;
        i64 bb = b;
        for (const auto e : c)
        {
            ret += iabs(e - t);
            bb += e - t;
        }
        return bb < 0 ? inf + t : ret;
    };

    i64 l = -1, r = 1e10;
    while (r - l > 2)
    {
        i64 ll = (l + l + r) / 3;
        i64 rr = (l + r + r) / 3;
        if (f(ll) > f(rr))
            l = ll;
        else
            r = rr;
    }

    std::cout << f((l + r) / 2) << std::endl;
}