#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll B,N,A[10];
ll getLim(){
    ll ret=B;
    for(int i=0;i<N;i++)ret+=A[i];
    return ret;
}
ll ll_abs(ll val){
    return val>0?val:val*-1;
}
int main(){
    scanf("%lld%lld",&B,&N);
    for(int i=0;i<N;i++)scanf("%lld",&A[i]);

    ll lim=getLim();
    sort(A,A+N);

    vector<ll>to;
    if(A[(N-1)/2]>lim)to.push_back(lim);
    else{
        for(int i=0;i<=1;i++){
            to.push_back(A[(N-i)/2]);
        }
    }

    ll ans=LLONG_MAX;
    for(int i=0;i<to.size();i++){
        ll sum=0;
        for(int j=0;j<N;j++){
            sum+=ll_abs(A[j]-to[i]);
        }
        ans=min(ans,sum);
    }

    printf("%lld\n",ans);
    return 0;
}