#include<iostream>

 #include<cstdio>

 #include<string>

 using namespace std;

 int vis[];

 int n;

 string a;

 int main()

 {

     cin >> n;

     for(int i = ;i < n;i++)

     {

         cin >> a;

         vis[a[] - 'a']++;

     }

     int ans = ;

     for(int i =  ;i < ;i++)

     {

         int l = vis[i] / ,r = vis[i] - l;

         ans += l*(l - )/ + r * (r - )/;

     }

     cout << ans;

     return ;

 }