import math
n = int(input())
names = [0]*26
for _ in range(n):
student = input()
names[ord(student[0])-97] += 1
total = [x for x in names if x > 0]
pairs = 0
for i in total:
pairs += math.comb(math.ceil(i/2), 2) + math.comb(math.floor(i/2), 2)
print(pairs)
#include<bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define pb push_back
#define fastread() (ios_base:: sync_with_stdio(false),cin.tie(NULL));
using namespace std;
int main()
{
long long n;
char c;
map<char,int>mp;
map<char,int>:: iterator itr;
string s;
cin>>n;
while(n--){
cin>>s;
c = s[0];
mp[c]++;
}
int a,one,sec,sum = 0;
for(itr=mp.begin(); itr!=mp.end(); itr++){
a = itr->second;
one = (a / 2) + (a % 2);
sec = a/2;
while(one--){
sum += one;
}
while(sec--){
sum += sec;
}
}
cout<<sum<<endl;
return 0;
}
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