N,H=map(int,input().split())
ab=sorted([list(map(int,input().split())) for _ in range(N)],key=lambda x:(x[0],x[1]),reverse=True)
cnt=0
if N>1:
    for i in range(1,N):
        if ab[i][1]>ab[0][0]:
            H-=ab[i][1]
            cnt+=1
            if H<=0:
                break
if H>0:
    if ab[0][0]>=ab[0][1]:
        print(cnt+(H+ab[0][0]-1)//ab[0][0])
    elif H<=ab[0][1]:
        print(cnt+1)
    else:
        print(cnt+1+(H-ab[0][1]+ab[0][0]-1)//ab[0][0])