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#include<bits/stdc++.h>

using namespace std;

const long long INF = 1e18;

int binSearch(vector<long long>& v, long long add){
    int l = -1;
    int r = v.size() - 1;
    while(l < r){
        int m = (l + 1 + r)/2;
        if(v[m] + add >= 0){
            l = m;
        }else{
            r = m-1;
        }
    }
    return l;
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n; cin>>n;
    vector<long long> city(n);
    for(int i = 0; i < n; i++){
        cin>>city[i];
    }
    vector<long long> dp;
    long long add = 0;
    dp.push_back(0);
    add += city[0];
    for(int i = 1; i < n; i++){
        int j = binSearch(dp, add);
        if(dp[dp.size() - 1] + add >= 0){
            dp.push_back(-add);
        }else{
            dp.push_back(-INF);
        }
        if(j >= 0){
            dp[j+1] = -add;
        }
        add += city[i];
    }
    int j = binSearch(dp, add);
    if(j == -1){
        cout<<-1;
    }else{
        int result = n - 1 - j;
        cout<<result;
    }
    return 0;
}