#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma optimize("unroll-loops")
#define fast ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define all(x) x.begin(), x.end()
#define rll(x) x.rbegin(), x.rend()
#define COMP(x) x.erase(unique(all(x)), x.end())
#define MOD 1000000007
#define MOD2 998244353
#define sz(x) (ll)x.size()
typedef __int128_t lll;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll,ll> pll;
typedef pair<ll, pll> PP;
const ll Lnf = 2e18;
ll n;
ll a[1010101];
int main(){
fast;
cin>>n;
for(int i = 1 ; i <= n ; i++)cin>>a[i];
for(int i = 1 ; i <= n ; i++)a[i]+=a[i-1];
ll ans = 0;
for(int i = n ; i >= 1 ; i--)if(a[i]>=0){
for(int j = i-1 ; j >= 0 ; j--){
if(a[j]>a[i]){i=j+1; break; }
ans += a[i]-a[j];
}
}
cout<<ans;
}
