def my_sqrt(x):  
   if x<2: return x  
   left=1  
   right=int(x/2)+1  
   while left<=right:  
            mid=int((left+right)/2)  
            if mid*mid==x:  
                return mid  
            if mid*mid>x:  
                right=mid-1  
            else:  
                left=mid+1  
   return right  
  
print(my_sqrt(16)) 