import sys
from math import ceil
input = sys.stdin.readline
N, H = map(int, input().split())
A = []
B = []
for _ in range(N):
    a, b = map(int, input().split())
    A.append(a)
    B.append(b)
maxA = max(A)
B = [n for n in B if n > maxA]
sumB = sum(B)
print(ceil((H-sumB)/maxA)+len(B))
