It is easier to look @ Program here, This program will take O(N) time, so Answer is 1.
int count = 0;
int number(struct node *Root)
{
int left , right , total;
if(qwerty)
{
left =number(qwerty->left); // number of node in left
right =number(qwerty->right); // number of node in right
if( (left + right + 1) == 4 ) check requirement
{
count++;
}
total =1 + left + right ;
return total ;
}