#include <iostream>
#include <unordered_map>
#include <algorithm>
#include <set>
#include <string>
#include <vector>
#include <random>
#include <deque>
using namespace std;
mt19937 rng(420691273);
#define ll long long
const int MX = 5e3 + 5;
int n, v[MX], dp[MX][MX];
int main(){
cin.tie(0) -> sync_with_stdio(0);
cin >> n;
for(int i = 0; i < n; i ++) cin >> v[i];
for(int ps = 0; ps < n; ps ++){
for(int l = 1; l <= ps; l ++)
dp[l][ps] = max(dp[l][ps], dp[l - 1][ps]);
int up = 0, dn = 0, cnt = -1;
for(int l = ps, r = ps + 1; l >= 0 && r < n;){
if(up == dn){
cnt ++;
dp[ps + 1][r] = max(dp[ps + 1][r], dp[l][ps] + cnt);
dn += v[l --]; up += v[r ++];
}else if(up < dn)
up += v[r ++];
else if(up > dn)
dn += v[l --];
}
for(int r = ps + 1; r < n; r ++)
dp[ps + 1][r] = max(dp[ps + 1][r], dp[ps + 1][r - 1]);
}
int ans = 0;
for(int l = 0; l < n; l ++)
ans = max(ans, dp[l][n - 1]);
cout << ans << endl;
return 0;
}
