#include<bits/stdc++.h>
using namespace std;
long long n,t,v[35005];
long long sol,s,dp[35005],dw,d;
pair<long long,long long > w[35005];
int main()
{
    freopen("euro.in","r",stdin);
    freopen("euro.out","w",stdout);
    scanf("%lld%lld",&n,&t);
    s=0LL;
    dw=-1LL;
    for(long long i=1;i<=n;i++)
    {
        scanf("%lld",&v[i]);
        s=s+1LL*v[i];
        if(s<0)
        {
            w[++dw]=make_pair(s,i);
            s=0;
        }
    }
    if(dw==(-1) || w[dw].second!=n)
    {
        w[++dw]=make_pair(s,n);
    }
    for(int i=0;i<=dw;i++)
    {
        s=w[i].first;
        d=w[i].second;
        dp[i+1]=dp[i]+s*d-t;
        for(int j=(i-1);j>=0 && (i-j)*(i-j)<=t+200;j--)
        {
            s+=w[j].first;
            dp[i+1]=max(dp[i+1],dp[j]+s*d-t);
        }
    }
    printf("%lld\n",dp[dw+1]);
    return 0;
}