N,M=map(int,input().split())
if N==1:
  print('NaN')
  exit()
l=1
r=10**20
from math import isqrt
while True:
  if l==r:
    break
  m=(l+r)//2
  k=isqrt(((m+1)**2-1)//N)
  count=m-k
  if count>=M:
    r=m
  else:
    l=m+1
print(l)