146

#-*-coding:utf8;-*-
#qpy:2
#qpy:console

def mysqrt(a):
  if a == 0: return 0

  top = a
  bottom = 1
  x = (top + bottom) // 2

  while (top > bottom):
    if(x*x < a):
      bottom = x+1
    else:
      top = x-1
    x = (top + bottom) // 2

  while (x+1)*(x+1) <= a:
    x+=1
  while x*x > a:
    x-= 1
  return x

#*****************
a = int(input())
print(mysqrt(a))