51nod 1344

#include<iostream>
using namespace std;
int main()
{
    int n;

    while(cin>>n)
    {
       int  minn=999999999;
       long long total=0;
       int temp;
       for(int i=0;i<n;i++)
       {
           cin>>temp;
           total+=temp;
           if(minn>total)
            minn=total;
       }
       if(minn>=0)
        cout<<"0\n";
       else
        cout<<minn*-1<<endl;
    }
    return 0;
}