#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
const int N = 510;
const int inf = 1e9;
const int M = 1e7;
int n;
int dp[N][N][2];
int v[N];
int mark[M];
const int debug = 0;
int main(){
cin >> n;
for(int i = 1;i <= n;i++)
cin >> v[i];
for(int i = 1;i <= n;i++){
dp[1][i][0] = 0;
dp[1][i][1] = -inf;
}
for(int i = 1;i < n;i++){
for(int j = i;j < n;j++){
//
int t = 0;
int l = i, r = j;
vector <int> bons;
t += v[i];
for(int k = i+1;k <= j;k++){
bons.push_back(t);
mark[t] = 1;
t += v[k];
}
int res = 0;
dp[r+1][r+1][1] = max(dp[r+1][r+1][1], dp[l][r][0]);
t -= v[r+1];
for(int k = j+2;k <= n;k++){
if(t >= 0 and mark[t] == 1){
res++;
}
t -= v[k];
dp[r+1][k][1] = max(dp[r+1][k][1], dp[l][r][0]+res);
}
for(auto x : bons){
mark[x] = 0;
}
bons.clear();
//
t = 0;
t += v[r];
for(int k = r-1;k >= i;k--){
bons.push_back(t);
mark[t] = 1;
t += v[k];
}
if(debug and l == 3 and r == 4){
for(auto x : bons){
cout << x << ' ';
}
cout << endl;
}
res = 0;
t = v[r+1];
if(debug and l == 3 and r == 4) cout << t << ' ';
dp[r+1][r+1][0] = max(dp[r+1][r+1][0], dp[l][r][1] + res);
for(int k = r+2;k <= n;k++){
if(t < M){
if(mark[t] == 1){
res++;
}
}
t += v[k];
if(debug and l == 3 and r == 4 and k == 6){
cout << res << endl;
}
dp[r+1][k][0] = max(dp[r+1][k][0], dp[l][r][1]+res);
}
for(auto x : bons) mark[x] = 0;
bons.clear();
}
}
int res = 0;
for(int i = 0;i <= n;i++){
res = max(res, dp[i][n][0]);
res = max(res, dp[i][n][1]);
}
cout << res << endl;
return 0;
}
