N = int(input())
for i in range(N):
s = input().lower()
d = {}
for i in s:
if i not in d:
d[i] = s.count(i)
ss = sorted(d.values(),reverse=True)
pld = 0
for k in range(len(ss)):
pld += (26-k)*ss[k]
print(pld)

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