def minRot(arr):
    if not arr: return -1
    n = len(arr[0])
    cnt = {(arr[0][i:] + arr[0][:i]) : i for i in range(n)}
    for s in arr[1:]:
        if len(s) != n: return -1
        for i in range(n):
            cur = s[i:] + s[:i]
            if cur not in cnt: return -1
            cnt[cur] += i
    return cnt[min(cnt, key = lambda x: cnt[x])]
n = int(input())
arr = []
for i in range(n):
    arr.append(input())
print(minRot(arr))