#include <cstdio>

using namespace std;

int v[501],v1[501];

int min1(int a,int b)
{
    if (a<b) return a;
    return b;
}

int main()
{
    freopen("podm.in","r",stdin);
    freopen("podm.out","w",stdout);
    int n;
    scanf("%d ",&n);
    ///4
    ///(13 5) (5 89) (89 3) (3 34)
    for (int i=1;i<=n+1;i++)
    {
        scanf("%d ",&v[i]);
        if (i>3)
        {
            v1[i]=min1(v[i]*v[i-1]*v[i-2]+v1[i-3]+v[1]*v[i-2]*v[i],v[1]*v[i-1]*v[i]+v1[i-1]);
        }
        else v1[i]=0;
    }
    printf("%d",v1[n+1]);
}