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#include <vector>
#include <cstdio>
#include <stack>
#include <algorithm>
#include <queue>
#include <map>
#include <cmath>
#include <unordered_set>
#include <unordered_map>
#include <set>
#include <cstring>
#include <bitset>
#include <iostream>
#include <queue>
#include <iomanip>
#include <complex>

using namespace std;

#define ALL(x) x.begin(), x.end()
#define UNIQUE(c) (c).resize(unique(ALL(c)) - (c).begin())
#define FOR(i, a, b) for(int i =(a); i <=(b); ++i)
#define RE(i, n) FOR(i, 1, n)
#define RED(i, n) FORD(i, n, 1)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)
#define REP(i, n) for(int i = 0;i <(n); ++i)
#define REPD(i, n) FORD(i, n-1,0)


const int maxn = 510, maxm = 1010;
const long long mod = 998244353, inf = 1000000004000000004ll;

int n,m, a[maxn], mi = 20001, b[maxn * maxn], il, t[20000002];
long long res;
void solve() {
    cin>>n;
    REP(i, n) {
        cin>>a[i];
    }
    REP(po, n) {
        int su = 0;
        FOR(ko, po, n - 1){
            su += a[ko];
            b[il] = su;
            mi = min(mi, b[il++]);
        }
    }
    if(mi > 0) {
        cout<<"0\n";
        return;
    }
    REP(i, il){
        b[i] -= mi;
//        cout<<b[i]<<" ";
        t[b[i]]++;
    }
//    cout<<"\n";
    REP(i, il){
        REP(j, i){
            if(b[i] * 2 + b[j] == 3 * (-mi))res--;
            if(b[i] + b[j] * 2 == 3 * (-mi))res--;
            if(3 * (-mi) - b[i] - b[j] >= 0 && 3 * (-mi) - b[i] - b[j] < 20000002 && t[3 * (-mi) - b[i] - b[j]]) {
                res += t[3 * (-mi) - b[i] - b[j]];
//                cout<<b[i] + mi<<" "<<b[j] + mi<<" "<<t[3 * (-mi) - b[i] - b[j]]<<" "<<3 * (-mi) - b[i] - b[j]<<"\n";
            }
        }
    }
    cout<<res/3<<"\n";
}

int main() {
    ios_base::sync_with_stdio(false), cin.tie(nullptr);
    int tt = 1;
//    cin >> tt;
    while (tt--) {
        solve();
    }
    return 0;
}