def solve(self, A):
root=A
q=[]
q.append(root)
q.append(None)
arr=[]
sum1=0
maxy=0
while(q):
node=q.pop(0)
if(node!=None):
sum1+=node.val
if(node==None):
if(q!=[]):
q.append(None)
sum1=0
else:
if(node.left and node!=None):
q.append(node.left)
if(node.right and node!=None):
q.append(node.right)
maxy=max(sum1,maxy)
return(maxy)