Consider the C function foo and the binary tree shown. typedef struct node {…

Consider the C function foo and the binary tree shown.

    typedef struct node {
        int val;
        struct node *left, *right;
    } node;
    int foo(node *p) {
        int retval;
        if (p == NULL)
            return 0;
        else {
            retval = p->val + foo(p->left) + foo(p->right);
            printf("%d ", retval);
            return retval;
        }
    }

When foo is called with a pointer to the root node of the given binary tree, what will it print?