A_Police Requirts

////////////////          PRANTA KUMER PANDIT            ///////////////
//                      Test Case Less Template                       ||
//                                                                    ||
//      BANGLADESH  UNIVERSITY OF BUSINESS AND TECHNOLOGY             ||
//                          INTAKE 52                                 ||
//                      DEPARTMENT OF CSE                             ||
//||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
//                      So, WELCOME TO ISHAN'S PERADISE           //
//                (-.-) Want to be a Secret tool of next ICPC��(-.-)����//
 
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define pb   push_back
#define yes   cout<<"YES"<<endl
#define no   cout<<"NO"<<endl
#define all(x) (x).begin(), (x).end()
#define gcd(a,b)      __gcd(a,b)
#define lcm(a,b)  (a*b)/__gcd(a,b)
#define optimize() ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
 
void solve()
{
    int n;
    cin >> n;
    vector<int> arr(n);
    for (int i = 0; i < n; i++)
    {
        cin >> arr[i];
    }
    int f= 0;
    int u = 0;
    for (int i = 0; i < n; ++i)
    {
        if (arr[i] == -1)
        {
            if (f > 0)
                f--;
            else
                u++;
        }
        else
        {
            f += arr[i];
        }
    }
 
    cout << u << endl;
}
 
int main()
{
    optimize();
    solve();
    return 0;
}
//                                   THANKS������������   ��������������//