#define _USE_MATH_DEFINES

#include <iostream>
#include <iomanip>

#include <algorithm>
#include <cmath>

#include <string>
#include <list>
#include <queue>
#include <vector>
#include <complex>
#include <set>

/////////
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i,n) REP(i,0,n)
#define P(p) cout<<(p)<<endl;
/////////
typedef long long LL;
typedef long double LD;
/////////
using namespace::std;
/////////

int main(void){
    std::cin.tie(0); 
    std::ios::sync_with_stdio(false);
    std::cout << std::fixed;//
    //cout << setprecision(6);//
    
	LL B,N;
	cin>>B>>N;
	LL C[10],Csum=0;
	rep(i,N){
		cin>>C[i];
		Csum += C[i];
	}
	sort(C,C+N);

	LL aveMax = (Csum+B)/N;
	LL aveMin = C[0];

	LL ans=-1;
	LL tans;
	for(LL aveP=aveMin;aveP<=aveMax;++aveP){
		tans = 0;
		for(int k=0;k<N;++k){
			if( C[k] < aveP){
				tans += aveP - C[k];
			}else{
				tans += C[k] - aveP;
			}
		}
		if(ans == -1|| ans>tans){
			ans = tans;
		}else{
			break;
		}
	}
	P(ans);
    return 0;
}