import sys
def check(mid):
res = 0
for i in range(N):
res += (H[i] // mid) (W[i] // mid)
if res >= K:
return True
return False

N,K = map(int,input().split())
H,W = [],[]
for i in range(N):
h,w = map(int,input().split())
H.append(h)
W.append(w)
l,r = 1, 10 * 5
while l < r:
mid = (l+r+1) >> 1
if check(mid):
l = mid
else:
r = mid - 1
print(l)