#include<cstdio>
#include<vector>


using namespace std;
using ll=long long;
using vi=vector<int>;
using vll=vector<ll>;


void solve_r(vi& v, vi& c, int m, int idx, ll ac, ll& result)
{
	vi w;

	if(ac>=result) return;
	if(idx>=v.size() || m==0)
	{
		if(m==0 && result>ac)
		{
			result=ac;
		}
		return;
	}

	w=v;
	for(int i=0;i<=m;i++)
	{
		w[idx]=v[idx]+i;
		if(w[idx]>w[idx-1]) break;

		solve_r(w, c, m-i, idx+1, ac+(ll)c[idx]*i, result);
	}
}


ll solve(vi& v, vi& c, int m)
{
	vi w;
	ll ret;

	ret=(ll)c[0]*m;
	w=v;
	for(int i=0;i<=m;i++)
	{
		w[0]=v[0]+i;
		solve_r(w, c, m-i, 1, (ll)c[0]*i, ret);
	}
	return ret;
}


int main(void)
{
	int n, v, i, m;
	vi c, w;
	vll s;
	double ave, min_ave;
	int min_idx, base_v;
	ll result;

	while(scanf("%d%d", &n, &v)==2)
	{
		s.resize(n);
		w.resize(n);
		c.resize(n);
		for(i=0;i<n;i++)
		{
			scanf("%d", &c[i]);
			w[i]=1;
			s[i]=((i>0)?s[i-1]:0)+c[i];
		}

		if(v<=n)
		{
			printf("%lld\n", s[n-1]);
			continue;
		}

		v-=n;

		min_ave=c[0];
		min_idx=0;
		for(i=1;i<n;i++)
		{
			ave=(double)s[i]/(i+1);
			if(min_ave>ave)
			{
				min_ave=ave;
				min_idx=i;
			}
		}

		base_v=v/(min_idx+1);
		m=v-base_v*(min_idx+1);
		for(i=0;i<=min_idx;i++)
		{
			w[i]+=base_v;
		}
		result=s[n-1]+s[min_idx]*base_v+solve(w, c, m);

		printf("%lld\n", result);
	}

	return 0;
}