twosum

//#include<bits/stdc++.h>
#include<iostream>
#include<fstream>
#include<vector>
#include<unordered_map>
#include<algorithm>

#define long int
#define nln '\n'

const long N = 1e5;

using namespace std;

// Global variables: f1, f2, n, a

fstream f1, f2;

inline void openf()
{
    f1.open("twosum.inp", ios:: in);
    f2.open("twosum.out", ios:: out);
}

inline void closef()
{
    f1.close();
    f2.close();
}

long n;
vector<long> a, sum;

void data()
{
    f1.tie(0)->sync_with_stdio(0);
    f2.tie(0)->sync_with_stdio(0);
    //cin.tie(0)->sync_with_stdio(0);
    cin >> n;
    a.resize(n+2, 0);
    sum.resize(n+2, 0);
    for (long i = 1; i-1 != n; ++i)
    {
        cin >> a[i];
        sum[i] = a[i] + sum[i-1];
    }
}

long total(long i, long j)
{
    return sum[j] - sum[i-1];
}

template<typename T>
void chmax(T &a, T b) {
  if (a < b) a = b;
}

long ans = 0;

void process()
{
    unordered_map<long, long> tic;
    tic[0] = 0;

    for (long i = 1; i <= n; i++)
    {
        for (long j = i+1; j <= n; j++)
        {
            long tol = sum[j]-sum[i];
            if (tic.count(sum[i]-tol))
                ans = max(ans, j-tic[sum[i]-tol]);
        }
        tic[sum[i]] = i;
    }
}

void view()
{
    cout << ans << nln;
}

int main()
{
    openf();
    data();
    process();
    view();
    closef();
    return 0;
}