T=0

N,H=map(int, input().split())

A=[]
B=[]
for i in range(N):
    a,b=map(int, input().split())
    A.append(a)
    B.append(b)

A.sort(reverse=True)

for i in range(N):
    if A[0]<=B[i]:
        H-=B[i]
        T+=1
        if H<=0:
            break

if H>0:
    T+=int(H/A[0])

print(T)
