N = int(input())

def check(word):
    flg = True
    mi, mx = 25, 0
    for s in word:
        if s < mx:
            flg = False
        mi = min(mi, s)
        mx = max(mx, s)
    return (flg, mi, mx, len(S))

lis = []

for i in range(N):
    S = [ord(x)-97 for x in input()]
    ok, mi, mx, ln = check(S)
    if ok:
        lis.append([mi, mx, ln])

lis.sort()
from collections import defaultdict

ans = 0
dp = [0] * 26
for mi, mx, leng in lis:
    if mi == mx:
        dp[mx] += leng
    else:
        dp[mx] = max(dp[mx], max(dp[:mi+1]) + leng)

print(max(dp))