#include <bits/stdc++.h>
using namespace std;
const int MAXN = 3e5 + 7;
const int inf = 1e9;
char s[60][60];
char s1[60];
int l;
int n;
int num[60];
int check(char *s) {
  for (int i = 0; i < l; ++i) {
    int j;
    for (j = 0; j < l; ++j) {
      if (s1[j] != s[(j + i) % l]) break;
    }
    if (j >= l) return i;
  }
  return -1;
}
int main() {
  scanf("%d", &n);
  for (int i = 0; i < n; ++i) scanf("%s", s[i]);
  l = strlen(s[0]);
  int ans = inf;
  for (int i = 0; i < l; ++i) {
    int sum = 0;
    for (int j = 0; j < l; ++j) s1[j] = s[0][(j + i) % l];
    for (int j = 0; j < n; ++j) {
      int t = check(s[j]);
      if (t == -1) {
        puts("-1");
        return 0;
      }
      sum += t;
    }
    ans = min(ans, sum);
  }
  printf("%d\n", ans);
  return 0;
}
