import math

count = 0

n, h = map(int, input().split(' '))
ab = [input().split(' ') for _ in range(n)]
 
max_a = int(sorted(ab, key=lambda x: int(x[0]), reverse=True)[0][0])
 
for x in sorted(ab, key=lambda x: x[1], reverse=True):
    if int(x[1]) > max_a:
        h -= int(x[1])
        count += 1

count += math.ceil(h / max_a)
 
print(count)