#include<bits/stdc++.h>
#define faster ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define ll long long
using namespace std;
int main()
{
    faster
    string s;
    ll n,i,d=0;
    cin>>n;
    ll t=0;
    vector<ll> a(n+1),f(2,0);
    for(i=1;i<=n;i++)
    {
        cin>>s;
        a[i]=s[s.size()-1]-'0';
    }
    f[0]=1;
    for(i=1;i<=n;i++)
    {
        t+=a[i];
        t%=2;
        d+=f[t];
        f[t]++;
    }
    cout<<d;
	return 0;
}

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6
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