n,m = [int(i) for i in input().split()]
l = [[int(i) for i in input().split()] for _ in range(n)]
l2 = sorted(l,key = lambda x :x[0])
min_atk = l2[n-1][0]

l3 = [i[1] for i in l if i[1] > min_atk]
ct = 0
for i in l3:
    if m > 0:
        m -= i
        ct += 1
    else:
        break

if m <= 0:
    print(ct)
else:
    q,r = divmod(m,min_atk)
    ct += (m//min_atk) +( 1 if r > 0 else 0 )
    print(ct)