a = [0] * 9999

n = int(input())
while n:
    n -= 1
    k, l = map(int, input().replace(':', '').split())
    a[k] += 1
    a[l + 1] -= 1

m = c = 0
for e in a:
    c += e
    m = max(m, c)

print(m)