#include<iostream>

#include<cstdio>

#include<cstring>

#include<algorithm>

#define maxn 1000050

using namespace std;

long long n,a[maxn],g[maxn],q[maxn],l,r,f[maxn];

long long read()

{

    char ch;long long data=;

    while (ch<'' || ch>'') ch=getchar();

    while (ch>='' && ch<='')

    {

        data=data*+ch-'';

        ch=getchar();

    }

    return data;

}

double k(long long x,long long y)

{

    return (double)(g[x]-g[y])/(x-y);

}

void dp()

{

    f[]=a[];l=r=;q[l]=;g[]=a[];

    for (long long i=;i<=n;i++)

    {

        while ((r-l) && (k(q[l],q[l+])<=i)) l++;

        g[i]=f[i-]+a[i]+i*(i-)/;

        while ((r-l) && (k(q[r-],q[r])>k(q[r],i))) r--;

        q[++r]=i;

        f[i]=f[q[l]-]+a[q[l]]+(i-q[l])*(i-q[l]+)/;

    }

}

int main()

{

    n=read();

    for (long long i=n;i>=;i--) a[i]=read();

    dp();

    printf("%lld\n",f[n]);

    return ;

}