
def main():
    N, H = map(int, input().split())

    A = []
    B = []

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

    C = []
    for b in B:
        if b > max(A):
            C.append(b)


    count = len(C)
    hp = H-sum(C)

    if hp <= 0:
        print (count)

    else:
        s = hp//max(A)
        if hp%max(A) != 0:
            s += 1
        print (count+s)


if __name__ == "__main__":
    # global stime
    # stime = time.clock()
    main()