#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <chrono>
#define _USE_MATH_DEFINES
#include <cmath>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
using namespace std;

#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()

const int INF = 0x3f3f3f3f;
const long long LINF = 0x3f3f3f3f3f3f3f3fLL;
const double EPS = 1e-8;
const int MOD = 1000000007;
// const int MOD = 998244353;
const int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
// const int dy[] = {1, 1, 0, -1, -1, -1, 0, 1},
//           dx[] = {0, -1, -1, -1, 0, 1, 1, 1};

struct IOSetup {
  IOSetup() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);
    cerr << fixed << setprecision(10);
  }
} iosetup;
/*-------------------------------------------------*/
int main() {
  map<long long, int> mp;
  FOR(i, 2, 200001) mp[1LL * i * (i - 1) / 2] = i;
  int n; cin >> n;
  vector<string> s(n); REP(i, n) cin >> s[i];
  vector<vector<long long> > wei(n);
  wei[0].assign(s[0].length(), 1);
  FOR(i, 1, n) {
    wei[i].assign(s[i].length(), 1);
    REP(j, s[i].length()) {
      if (s[i - 1][j] != s[i][j]) break;
      wei[i][j] = 1LL * mp[wei[i - 1][j]] * (mp[wei[i - 1][j]] + 1) / 2;
    }
  }
  long long ans = 0;
  REP(i, n) ans += accumulate(ALL(wei[i]), 0LL);
  cout << ans << '\n';
  return 0;
}