#include <bits/stdc++.h>
using namespace std;
#define fastcin {\
    cin.tie(0);\
    ios::sync_with_stdio(false);\
}
#define rep(i, a, b) for(int i = a; i < b; i++)
#define print(x) cout << x << "\n"
#define VSORT(v) sort(v.begin(), v.end());
typedef long long ll;
typedef vector<ll> vll;

int main() {
    fastcin;
    ll b, n, in, mid, ans = 0;
    cin >> b >> n;
    vll c;
    rep(i, 0, n) {
        cin >> in;
        c.push_back(in);
    }
    VSORT(c);
    mid = c[n/2];
    rep(i, 0, n/2) ans += mid-c[i];
    rep(i, n/2+1, n) ans += c[i]-mid;
    print(ans);
    return 0;
}