def main():
    from math import ceil
    from itertools import accumulate
    from bisect import bisect_right
    n, h, *ab = map(int, open(0).read().split())
    x = list(accumulate(ab[1::2]))
    if x[-1] < h:
        print(ceil((h-x[-1])/max(ab[::2])) + n)
    else:
        i = bisect_right(x, h)
        print(i)

if __name__ == '__main__':
    main()
