#include <bits/stdc++.h>
using namespace std;
using ll =long long;
int main() {
	// your code goes here
	ll n;
	cin>>n;
	vector<ll>a(n);
	for(ll i=0;i<n;i++) cin>>a[i];
	unordered_map<int,int> prefFreq;
	unordered_map<int,int> suffFreq;
	int sum=0;
	for(int i=0;i<n;i++)  sum+=a[i];
	int cnt=0;
	if(sum%4!=0){
		cout<<0<<endl;
		return 0;
	}
	else{
		ll pref=a[0];
		prefFreq[a[0]]=1;
	
		ll suff=0;
		for(ll i=n-1;i>=3;i--){
			suff+=a[i];
			suffFreq[suff]++;
		}
		suff+=a[2];
		pref+=a[1];
		ll y=sum/4;
		for(int i=1;i<=n-3;i++){
			if(pref==2*y && suff==2*y){
				//1st and 4 quater
				cnt+=(prefFreq[y]*suffFreq[y]);
				// cout<<cnt<<" "<<i<<endl;
			}
			prefFreq[pref]++;
			pref+=a[i+1];
			suff-=a[i+1];
			suffFreq[suff]--;
			
		}
	}
	cout<<endl;
	cout<<cnt<<endl;
	return 0;
}