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#include <bits/stdc++.h>
#define ll long long int
#define pb push_back
#define st first
#define nd second
#define pii pair<int,int>
#define mp make_pair
#define pll pair<long long,long long>

using namespace std;

const int nax = 1e6 + 5;
ll a[nax];
ll pref[nax];
int n;

// from cp algorithms

struct FenwickTreeMin {
    vector<int> bit;
    int n;
    const int INF = (int)-1e9;

    FenwickTreeMin(int n) {
        this->n = n;
        bit.assign(n, INF);
    }

    FenwickTreeMin(vector<int> a) : FenwickTreeMin(a.size()) {
        for (size_t i = 0; i < a.size(); i++)
            update(i, a[i]);
    }

    int getmin(int r) {
        int ret = INF;
        for (; r >= 0; r = (r & (r + 1)) - 1)
            ret = max(ret, bit[r]);
        return ret;
    }

    void update(int idx, int val) {
        for (; idx < n; idx = idx | (idx + 1))
            bit[idx] = max(bit[idx], val);
    }
};

int dp[nax];

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0);
    cin>>n;
    for(int i=1;i<=n;i++) cin>>a[i];
    for(int i=1;i<=n;i++) pref[i] = pref[i - 1] + a[i];

    set<ll> values;
    for(int i=0;i<=n;i++) values.insert(pref[i]);

    vector<ll> uni;
    for(ll akt : values)
    {
        uni.pb(akt);
    }

    for(int i=0;i<=n;i++)
    {
        pref[i] = lower_bound(uni.begin(),uni.end(),pref[i]) - uni.begin();
    }

    dp[0] = 0;
    FenwickTreeMin drzewko(n + 5);
    drzewko.update(pref[0], 0);

    for(int i=1;i<=n;i++)
    {
        int cur = pref[i];

        int pop = drzewko.getmin(cur);

        dp[i] = pop + 1;

        drzewko.update(cur,dp[i]);
    }
    if(dp[n] == 0) cout<<-1<<"\n";
    else cout<<n - dp[n]<<"\n";

    return 0;
}