#include <bits/stdc++.h>
#define ll long long
using namespace std;
ll dp[110][110];
ll currsumdp[110][110];
ll sum=0;
ll helper(ll i,ll n,ll part,ll curr,ll totsum,vector<ll>&a)
{
    if(i!=n and part==4) return 0;
    if(i==n) return(part==4)?1:0;
    if(currsumdp[i][part]) return dp[i][part];
    curr+=a[i];
    currsumdp[i][part]=1;
   return dp[i][part]=helper(i+1,n,part,curr,totsum,a)+((curr==(totsum/3)*part)?helper(i+1,n,part+1,curr,totsum,a):0);

}
ll solve(vector<ll>&a)
{
    ll n=a.size();
    for(auto it:a) sum+=it;
    if(n<3 or sum%3) return 0;
    memset(dp,-1,sizeof(dp));
    return helper(0,n,1,0,sum,a);
}
signed main() {
    ll n; cin>>n;
    vector<ll>a(n);
    for(ll i=0;i<n;i++) cin>>a[i];
    cout<<solve(a);
    return 0;
}

#include <bits/stdc++.h>
#define ll long long
using namespace std;
ll solve(vector<char>&a)
{
    stack<char>st;
    ll n=a.size();
    ll i=0;
    while(i<n)
    {
        if(a[i]=='P')
        {
            i++;
            st.push(a[i]);
        }
        else if(a[i]=='B')
        {
            i++;
            if(st.top()==a[i]) st.pop();
            else break;
        }
        i++;
    }
    if(st.empty()) return -1;
    return st.size()+1;
}
signed main() {
     
     string s;
     getline(cin,s);
     vector<char>a;
     for(auto it:s)
        if(it!=' ') a.push_back(it);
     cout<<solve(a);

    return 0;
}