while True:
try:
n = int(input())
names = []
for i in range(n):
names.append(input().lower())
for name in names:
zimu = {x:name.count(x) for x in name}
zimu = sorted(zimu.items(), key = lambda kv:(kv[1], kv[0]),
reverse=True)
s = 27
z = 0
for (_,i) in zimu:
s -= 1
z += s * i
print(z)
except:
break