n, h = map(int, input().split())
katana = [list(map(int, input().split())) for i in range(n)]

th_sum = 0
for i in range(n):
    th_sum += katana[i][1]

if th_sum >= h:
    for i in range(n):
        if h > 0:
            h -= katana[i][1]
        else:
            print(i)
            exit()
    print(n)
    exit()
else:
    sw_max = 0
    sw_i = 0
    for i in range(n):
        if katana[i][0] > sw_max:
            sw_max = katana[i][0]
            sw_i = i

    count = n - 1
    h -= (th_sum + katana[sw_i][0] - katana[sw_i][1])
    if h % sw_max == 0:
        count += h//sw_max
    else:
        count += h//sw_max + 1
    print(count)
