#pragma GCC optimize ("O3")
#pragma GCC target ("avx")
#include "bits/stdc++.h" // define macro "/D__MAI"

using namespace std;
typedef long long int ll;

#define xprintf(fmt,...) fprintf(stderr,fmt,__VA_ARGS__)
#define debugv(v) {printf("L%d %s > ",__LINE__,#v);for(auto e:v){cout<<e<<" ";}cout<<endl;}
#define debuga(m,w) {printf("L%d %s > ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<<endl;}
#define debugaa(m,h,w) {printf("L%d %s >\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[y][x]<<" ";}cout<<endl;}}
#define ALL(v) (v).begin(),(v).end()
#define repeat(cnt,l) for(auto cnt=0ll;(cnt)<(l);++(cnt))
#define iterate(cnt,b,e) for(auto cnt=(b);(cnt)!=(e);++(cnt))
#define MD 1000000007ll
#define PI 3.1415926535897932384626433832795
#define EPS 1e-12
template<typename T1, typename T2> ostream& operator <<(ostream &o, const pair<T1, T2> p) { o << "(" << p.first << ":" << p.second << ")"; return o; }
template<typename iterator> inline size_t argmin(iterator begin, iterator end) { return distance(begin, min_element(begin, end)); }
template<typename iterator> inline size_t argmax(iterator begin, iterator end) { return distance(begin, max_element(begin, end)); }
template<typename T> T& maxset(T& to, const T& val) { return to = max(to, val); }
template<typename T> T& minset(T& to, const T& val) { return to = min(to, val); }

mt19937_64 randdev(8901016);
inline ll rand_range(ll l, ll h) {
    return uniform_int_distribution<ll>(l, h)(randdev);
}

#ifdef __MAI
#define getchar_unlocked getchar
#define putchar_unlocked putchar
#endif
#ifdef __VSCC
#define getchar_unlocked _getchar_nolock
#define putchar_unlocked _putchar_nolock
#endif
namespace {
#define isvisiblechar(c) (0x21<=(c)&&(c)<=0x7E)
    class MaiScanner {
    public:
        template<typename T> void input_integer(T& var) {
            var = 0;
            T sign = 1;
            int cc = getchar_unlocked();
            for (; cc<'0' || '9'<cc; cc = getchar_unlocked())
                if (cc == '-') sign = -1;
            for (; '0' <= cc&&cc <= '9'; cc = getchar_unlocked())
                var = (var << 3) + (var << 1) + cc - '0';
            var = var*sign;
        }
        inline int c() { return getchar_unlocked(); }
        inline MaiScanner& operator>>(int& var) {
            input_integer<int>(var);
            return *this;
        }
        inline MaiScanner& operator>>(long long& var) {
            input_integer<long long>(var);
            return *this;
        }
        inline MaiScanner& operator>>(string& var) {
            int cc = getchar_unlocked();
            for (; !isvisiblechar(cc); cc = getchar_unlocked());
            for (; isvisiblechar(cc); cc = getchar_unlocked())
                var.push_back(cc);
            return *this;
        }
        template<typename IT> void in(IT begin, IT end) {
            for (auto it = begin; it != end; ++it) *this >> *it;
        }
    };
}
MaiScanner scanner;


// 三分探索 しさくひん
// funcを最小化する値を求める．
// funcの極値は1つであること
// かなり無駄がありそう
ll t_search_proto(ll left, ll right, auto func) {

    repeat(_,150) {

        ll l = right - (2 * right - 2 * left) / 3;
        ll r = right - (right - left) / 3;

        ll lval = func(l);
        ll rval = func(r);
        // printf("%lld %lld ; %lld->%lld %lld->%lld\n", left, right,l,lval,r,rval);

        if (lval <= rval) {
            right = r;
        }
        else {
            left = l;
        }
        if (left == right)
            return left;
    }
    ll best = func(left);
    ll bestidx = left;
    for (ll t = left + 1; t <= right; ++t) {
        ll f = func(t);
        if (best > f) {
            best = f; bestidx = t;
        }
    }
    return bestidx;
}


ll m, n, kei;

ll cc[20];

int main() {

    scanner >> m >> n;
    scanner.in(cc, cc + n);

    ll best = t_search_proto(0ll, (ll)2e10, [&](ll x) {
        ll ctrl = 0;
        ll hand = m;
        repeat(i, n)
            if (cc[i] > x)
                hand += cc[i] - x,
                ctrl += cc[i] - x;
        repeat(i, n)
            if (cc[i] < x)
                hand -= x - cc[i],
                ctrl += x - cc[i];

        if (hand < 0) ctrl += 5e15; // NG
        return ctrl;
    });

    ll ans = 0;

    repeat(i, n)
        ans += abs(cc[i] - best);

    cout << ans << endl;

    return 0;
}