n, h = map(int,input().split())
a = []
b = []
for i in range(n):
    ca, cb = map(int,input().split())
    a.append(ca)
    b.append(cb)

a.sort(reverse=True)
b.sort(reverse=True)
cnt = 0
while h > 0:
    if b[0] > a[0]:
        h -= b.pop(0)
        cnt += 1
    else:
        cnt += h//a[0]
        h -= a[0] * h//a[0]
        if h > 0:
            h -= a[0]
            cnt += 1
print(cnt)