#include <iostream>
#include <vector>
#include <array>
#include <list>
#include <string>
#include <stack>
#include <queue>
#include <deque>
#include <unordered_map>
#include <unordered_set>
#include <tuple>
#include <memory>
#include <cmath>
#include <algorithm>
#include <functional>
#include <iomanip>
#include <numeric>
#include <climits>
#include <cfloat>
#include <cassert>
#include <random>

int main() {
	int n; std::cin >> n;
	std::vector<std::string> words(n); for (auto& w : words) std::cin >> w;
	std::queue<std::pair<int, int>> queue;
	const auto max_length = std::max_element(words.begin(), words.end(), [](const std::string& a, const std::string& b) { return a.size() < b.size(); })->size();
	queue.emplace(0, n);
	long long int result = 0;
	for (auto i = 0; i < max_length; ++i) {
		for (auto size = queue.size(); size > 0; --size) {
			const auto top = queue.front(); queue.pop();
			int prev = -1;
			for (auto j = top.first; j < top.second; ++j) {
				if (i >= words[j].size()) {
					if (prev != -1) {
						queue.emplace(prev, j);
						result += (j - prev) * (j - prev + 1LL) * (j - prev + 2LL) / 6;
						prev = -1;
					}
				}
				else if (prev != -1) {
					if (words[prev][i] != words[j][i]) {
						queue.emplace(prev, j);
						result += (j - prev) * (j - prev + 1LL) * (j - prev + 2LL) / 6;
						prev = j;
					}
				}
				else {
					prev = j;
				}
			}
			if (prev != -1) {
				queue.emplace(prev, top.second);
				result += (top.second - prev) * (top.second - prev + 1LL) * (top.second - prev + 2LL) / 6;
			}
		}
	}
	std::cout << result << std::endl;
}