import numpy as np
N,H=map(int,input().split())
ab=[input().split() for i in range(N)]
a = [int(ab[i][0]) for i in range(N)]
maxa = max(a)
b = np.array([int(ab[i][1]) for i in range(N)])
b_effective = b[b > maxa]
c = len(b_effective)
rest = H-sum(b_effective)
if rest % maxa == 0:
 d = rest//maxa
else:
 d = rest//maxa + 1
print(c+d)