from math import ceil
N,H=map(int,input().split())
AB=[list(map(int,input().split())) for i in range(N)]
sw=max(AB[i][0] for i in range(N))
cnt=0
for i in range(N):
    if AB[i][1]>=sw:
        cnt+=1
        H-=AB[i][1]
        if(H<=0):
            print(cnt)
            exit()
cnt+=ceil(H/sw)
print(cnt)