n = int(input())
s = [input().strip() for i in range(n)]
 
ss = [si+si for si in s]	# save strings concatenated to themselves
best = 10**9
T = s[0]	# initially target string is s[0]
for i in range(len(T)):
	total_steps = 0
	for S in ss:
		steps = S.find(T)	# finds occurence of T in S
		if steps==-1:		# not found, hence impossible
			best = -1
			break
		total_steps += steps
	if best==-1:	# impossible
		break
	best = min(total_steps, best)
	T = T[1:]+T[:1]		# cyclic shift T to get next rotation
 
print(best)

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

NAp4enp3bwp6d294egp6endveAp4enp3bw==

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