import math
n, h = map(int,input().split())
a,b=0,[]
for i in range(n):
    k,l = map(int,input().split())
    a = max(a,k)
    b.append(l)
b.sort(reverse=True)
cnt=0
idx = 0
while(h>0):
    if idx<len(b) and b[idx]>a:
        h -= b[idx]
        idx += 1
        cnt += 1
    else:
        cnt += math.ceil(h/a)
        h=0
print(cnt)