швб_22-23_N3

#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <string>
#include <stack>
#include <set>
#include <map>
#define pii pair <int, int>
#define pb(x) push_back(x)
using namespace std;
using ll = long long;
using ld = long double;
using db = double;
void cv(vector <int> &v) {
    for (auto x : v) cout << x << ' ';
    cout << "\n";
}

void cvl(vector <ll> &v) {
    for (auto x : v) cout << x << ' ';
    cout << "\n";
}


void cvv(vector <vector <int> > &v) {
    for (auto x : v) cv(x);
    cout << "\n";
}

void cvb(vector <bool> v) {
    for (bool x : v) cout << x << ' ';
    cout << "\n";
}

void cvs(vector <string>  v) {
    for (auto a : v) {
        cout << a << "\n";
    }
}

void cvp(vector <pii> a) {
    for (auto p : a) {
        cout << p.first << ' ' << p.second << "\n";
    }
    cout << "\n";
}

bool sh = 0;

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n; cin >> n;
    vector <int> a(n), pf(n);
    for (int &i: a) cin >> i;
    if (n < 3) {
        cout << 0;
        exit(0);
    }
    pf[0] = a[0];
    for (int i = 1; i < n; ++i) {
        pf[i] = pf[i - 1] + a[i];
    }
    if (sh) {
        cout << "a pf\n";
        cv(a);
        cv(pf);
    }
    for (int i = 0; i <= n - 2; ++i) {
        for (int j = i + 1; j <= n - 2; ++j) {
            int a, b, c;
            a = pf[i];
            b = pf[j] - pf[i];
            c = pf[n - 1] - pf[j];
            if (a == b && a == c) {
                int l1 = i + 1, l2 = j - i, l3 = n - 1 - j;
                int ans = max(l1, l2);
                ans = max(ans, l3);
                cout << ans;
                exit(0);
            }
        }
    }
    cout << 0;
}
/*
5
1 1 1 1 2
*/