from sys import stdin
import math
N,H = [int(x) for x in stdin.readline().rstrip().split()]
swing = []
throw = []
for _ in range(N):
    a,b = [int(x) for x in stdin.readline().rstrip().split()]
    swing.append(a)
    throw.append(b)
swing_m = max(swing)
throw_l = [i for i in throw if i >= swing_m]
ans = (H - sum(throw_l))/swing_m
ans = math.ceil(ans)
print(ans+len(throw_l))