//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
#define rep(i, n) for(int i=0; i<n; ++i)
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
using namespace std;
using ll = int64_t;
using ld = long double;
using P = pair<int, int>;
using vs = vector<string>;
using vi = vector<int>;
using vvi = vector<vi>;
template<class T> using PQ = priority_queue<T>;
template<class T> using PQG = priority_queue<T, vector<T>, greater<T> >;
const int INF = 0xccccccc;
const ll LINF = 922337203685477580LL;
template<typename T1, typename T2>
inline bool chmax(T1 &a, T2 b) {return a < b && (a = b, true);}
template<typename T1, typename T2>
inline bool chmin(T1 &a, T2 b) {return a > b && (a = b, true);}
template<typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) { return is >> p.first >> p.second;}
template<typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) { return os << p.first << ' ' << p.second;}

const int N = 2e5+10;

//head

int n;
string s[N];

ll dfs(int l, int r, int now) {
	ll res = 0;
	for(int i = l; i < r; i++) if(s[i].size() != now) {
		int j = i;
		char c = s[i][now];
		while(j < r and s[j].size() != now and s[j][now] == c) j++;
		int u = j-i;
		res += (ll)u*(u+1)*(u+2)/6 + dfs(i, j, now+1);
		i = j-1;
	}
	return res;
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cin >> n;
	rep(i, n) cin >> s[i];

	cout << dfs(0, n, 0) << endl;
}