#include <bits/stdc++.h>
#define ll long long

using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    #ifndef ONLINE_JUDGE
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    #endif
    int n;
    cin>>n;
    ll a[n+1];
    a[0] = 0;
    for(int i=1; i<=n; i++){
        cin>>a[i];
        a[i] += a[i-1];
    }
    ll total = a[n];
    if(total % 3){
        cout<<0<<endl;
        return 0;
    }
    vector <int> blk1;
    int cnt = 0;
    for(int i=1; i<n-1; i++){
        if(a[i] == total/3){
            cnt++;
            blk1.push_back(i);
        }
    }
    
    int cnt2 = 0;
    for(int idx: blk1){
        for(int i=idx+1; i<n; i++){
            if(a[i] - a[idx] == total/3 && a[n] - a[i] == total/3)
                cnt2++;
        }
    }
    cout<<cnt2<<endl;
    return 0;
}