n, h = map(int,input().split())
a=[]
b=[]
temp=[0,0]
count = 0
for _ in range(n):
	temp[0], temp[1] = map(int,input().split())
	a.append(temp[0])
	b.append(temp[1])
max = max(a)
for i in range(n):
	if b[i]>max:
		h -= b[i]
		count+=1
if h%max == 0:
	count+=h/max
else:
	count+=h/max+1
	
print(int(count))