#include <iostream>
#include <math.h>
#include <vector>
#include <array>
#include <algorithm>
#include <queue>
#include <numeric>
#include <map>
#include <set>

using namespace std;
#define int long long
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define array2(type, x, y) array<array<type, y>, x>
#define vector2(type) vector<vector<type> >
#define out(...) //printf(__VA_ARGS__)

typedef pair<int, int> pos;
int pos::*x = &pos::first;
int pos::*y = &pos::second;

int dxy[] = {0, 1, 0, -1, 0};

/*================================*/
int B, N;
int C[10];

int count(int c) {
    int cnt = 0;
    REP(i,N) cnt += abs(c - C[i]);
    return cnt;
}

signed main()
{
    cin >> B >> N;
    REP(i,N) cin >> C[i];
    
    // キャンディー全部でいくつか
    int total = B;
    int maxnum = 0;
    REP(i,N) {
        total += C[i];
    }
    // 一個あたりに入れられる最大数
    maxnum = total / N;
    
    // 三分探索の実装
    int maxb = maxnum;
    int minb = 0;
    while (true) {
        int bigb = minb + (maxb - minb) * 2 / 3;
        int smallb = minb + (maxb - minb) * 1 / 3;
        int bigc = count(bigb);
        int smallc = count(smallb);
        if (bigc > smallc) {
            maxb = bigb;
        } else {
            minb = smallb;
        }
        if (maxb - minb < 5) break;
    }
    int minc = pow(10, 11);
    FOR(i,minb,maxb+1) {
        minc = min(minc, count(i));
    }
    
    cout << minc << endl;
    
    return 0;
}