n, h = list(map(int, input().split(' ')))
a, b = [list(map(int, input().split(' '))) for _ in range(n)]

a.sort(reverse = True)
b.sort(reverse = True)
a.append(0)
b.append(0)
count = 0
x = 0
y = 0

while h < 0:
    if a[x] <= b[y]:
        h -= b[y]
        y += 1
        count += 1
    elif a[x] > b[y]:
        h -= a[x]
        count += 1
print(count)