#include<bits/stdc++.h>
using namespace::std;
typedef long long LL;
typedef pair<int, int> PI;
typedef pair<LL, LL> PL;

int main(){
    LL B, N;
    cin >> B >> N;
    vector<LL> c(N);
    LL csum = 0;
    for(int i = 0;i < N;i++)    {
        cin >> c[i];
        csum += c[i];
    }
    sort(c.begin(), c.end());
    int mid = max((int)(N/2-N^1), 0);
    LL ans = 0;
    LL cm = min((csum+B)/N, c[mid]);
    for(int i = 0;i < N;i++){
        ans += abs(c[i]-cm);
    }
    cout << ans << endl;
}