#include <iostream>
#include <algorithm>
#include <array>
#include <bitset>
#include <cstring>
#include <deque>
#include <math.h>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <queue>
#include <vector>

#define FOR(i, a, b) for(int (i) = (a); (i) < (b); ++(i))
#define rFOR(i, a, b) for(int (i) = (b); (i) >= (a); --(i))
#define REP(i, n) FOR(i, 0, n)
#define rREP(i, n) rFOR(i, 0, (n-1))
#define SORT(A) std::sort((A).begin(), (A).end())
#define ALL(A) (A).begin(), (A).end()
// 座標圧縮 (for vector) : ソートしてから使うのが一般的 ; SORT(A) => COORDINATE_COMPRESSION(A)
#define COORDINATE_COMPRESSION(A) (A).erase(unique((A).begin(),(A).end()),(A).end())

using lli = long long int;
using pii = std::pair<int, int>;

void VintOut(std::vector<int>& A){
    const int n = A.size();
    if(n == 0){putchar('\n'); return;}
    printf("%d", A[0]);
    for(int i = 1; i < n; ++i) printf(" %d", A[i]);
    putchar('\n');
}
void VintOut(std::vector<long long int>& A){
    const int n = A.size();
    if(n == 0){ putchar('\n'); return;}
    printf("%lld", A[0]);
    for(int i = 1; i < n; ++i) printf(" %lld", A[i]);
    putchar('\n');
}

template <typename T>
inline bool chmin(T& a, T b){
    if(b < a){ a = b; return true;}
    return false;
}

template <typename T>
inline bool chmax(T& a, T b){
    if(a < b){ a = b; return true;}
    return false;
}


// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

constexpr int N = 2e5;
char s[2][N+10];
std::array<lli, N+10> A[2];

int main(void){
    int n; scanf("%d", &n);
    lli res = 0;
    int slen, plen = 0;
    REP(_, n){
        int working = (_ & 1), prev = 1 ^ working;
        scanf("%s", s[working]); slen = strlen(s[working]);
        int idx = 0; int l = (slen > plen) ? plen : slen;
        while(idx < l){
            if(s[working][idx] != s[prev][idx]) break;
            A[working][idx] = A[prev][idx] + 1;
            res += A[working][idx] * (A[working][idx] + 1) / 2;
            idx++;
        }
        while(idx < slen){
            A[working][idx] = 1;
            res++;
            idx++;
        }
        plen = slen;
    }
    printf("%lld\n", res);

    
    return 0;
}