boj-1931. 회의실배정

def fn(x):
    return x[0]

mettings = []

for _ in range(int(input())):
    start, end = map(int, input())
    mettings.append((end, start))

mettings = sorted(mettings, key=fn)

t = 0 
mettings_cnt = 0
for end, start in mettings:
    if t <= start :
        mettings_cnt += 1
        t = end