import numpy as np
n,h = map(int,input().split())
a,b=np.array([0]*n),np.array([0]*n)
for i in range(n):
    a[i],b[i] = map(int,input().split())
amax=max(a) 
b2=b[b>amax]
print((h-sum(b2)+amax-1)//amax + len(b2))