#pragma GCC optimize("O3,unroll-loops")
#include <bits/stdc++.h>
using namespace std;

#ifdef WAIMAI
#define debug(HEHE...) cout << "[" << #HEHE << "] : ", dout(HEHE)
void dout() {cout << '\n';}
template<typename T, typename...U>
void dout (T t, U...u) {cout << t << (sizeof... (u) ? ", " : ""), dout (u...);}
#else
#define debug(...) 7122
#endif

#define ll long long
#define Waimai ios::sync_with_stdio(false), cin.tie(0)
#define FOR(x,a,b) for (int x = a, I = b; x <= I; x++)
#define pb emplace_back
#define F first
#define S second

const int SIZE = 1505;
const int MAX = 26 * 26 * 26 * 26 + 5;

int n, ans;
vector<string> v[21];
string s[SIZE];
int cnt[21][MAX];

void solve() {
    cin >> n;
    FOR (i, 1, n) {
        cin >> s[i];
        v[s[i].size()].pb(s[i]);
    }
    FOR (len, 1, 20) if (v[len].size()) {
        n = v[len].size();
        FOR (i, 0, n - 1) s[i + 1] = v[len][i];
        FOR (i, 1, n) FOR (j, i + 1, n) {
            int p = -1, c = 0;
            FOR (k, 0, s[i].size() - 1) if (s[i][k] != s[j][k]) {
                c++;
                p = k;
            }
            if (c == 2 && s[i][p - 1] != s[j][p - 1]) {
                string t;
                t += min(s[i].substr(p - 1, 2), s[j].substr(p - 1, 2));
                t += max(s[i].substr(p - 1, 2), s[j].substr(p - 1, 2));
                int val = 0;
                for (char c : t) val = 26 * val + c - 'A';
                cnt[p - 1][val]++;
            }
        }
        FOR (i, 0, s[1].size() - 1) FOR (j, 0, MAX - 1) {
            ans += (cnt[i][j] == 1);
            cnt[i][j] = 0;
        }
    }
    cout << ans << '\n';
}

int main() {
    Waimai;
    solve();
}