#include <iostream>
#include <vector>
#include <string>
#include <functional>

using lint = long long;

void solve() {
    int n;
    std::cin >> n;

    std::vector<std::string> ss(n);
    for (auto& s : ss) {
        std::cin >> s;
        s.push_back('$');
    }

    lint ans = 0;
    std::function<void(int, int, int)> dfs =
        [&](int l, int r, int d) -> void {
        while (l < r && ss[l][d] == '$') ++l;
        if (l == r) return;

        int i = l;
        while (i < r && ss[i][d] == ss[l][d]) ++i;
        lint len = i - l;
        ans += len * (len + 1) * (len + 2) / 6;

        dfs(l, i, d + 1);
        dfs(i, r, d);
    };
    dfs(0, n, 0);

    std::cout << ans << "\n";
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}