#include <stdio.h>
#include <string>
#include <cstring>
#include <stdlib.h>
#include <math.h>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <list>
#include <iterator>
#include <assert.h>
#pragma warning(disable:4996) 
 
typedef long long ll;
#define MIN(a, b) ((a)>(b)? (b): (a))
#define MAX(a, b) ((a)<(b)? (b): (a))
#define LINF 9223300000000000000
#define INF 2140000000
const long long MOD = 1000000007;
//const long long MOD = 998244353;
using namespace std;

char str[2][200005];
int  len[2];
int  a[200005];

int main(int argc, char* argv[])
{
    int n;
    scanf("%d", &n);
    ll sum=0;
    int i,j;
    int prev=0, curr=1;
    for(i=0; i<n; i++) {
        scanf("%s", str[curr]);
        len[curr]=strlen(str[curr]);
        int same=1;
        for(j=0; j<len[curr]; j++) {
            if(i>0 && j<len[prev] && same && str[prev][j]==str[curr][j]) {
                a[j]=a[j]+1;
            }
            else {
                a[j]=1;
                same=0;
            }
            sum+=(ll)a[j]*(a[j]+1)/2;
        }
        swap(prev,curr);
    }
    printf("%lld\n", sum);


    return 0;
}