gistfile1.txt

struct t{struct t*l,*r;int x;};

extern puts();

int main(){
    struct t tree1 = { 0, 0, 1 };
    struct t tree3 = { 0, 0, 3 };
    struct t tree2 = { &tree1, &tree3, 2 };
    struct t tree5 = { 0, 0, 5 };
    struct t tree7 = { 0, 0, 7 };
    struct t tree6 = { &tree5, &tree7, 6 };
    struct t tree4 = { &tree2, &tree6, 4 };

    puts(f(&tree4)?"yes":"no");
}