while True:
try:
n = int(input())
names = [input() for _ in range(n)]
for name in names:
dic = {}
for c in name:
if c not in dic:
dic[c] = 1
else:
dic[c] += 1
lst = list(sorted(dic.values(), reverse=True))
total, point = 0, 26
for i in lst:
total += point * i
point -= 1
print(total)
except:
break