N,H=map(int,input().split())
ab=sorted([list(map(int,input().split())) for _ in range(N)],key=lambda x:x[1],reverse=True)
a_M=max([ab[i][0] for i in range(N)])

ans =0
for a,b in ab:
    if b <= a_M:
        break
    H -= b
    ans += 1
    if H<=0:break
if H>0:
    ans += (H-1)//a_M+1
print(ans)