B'Heidi has finally found the mythical Tree of Life xe2 x80 x93 a legendary combinatorial structure which is said to contain a prophecy crucially needed to defeat the undead armies. On the surface, the Tree of Life is just a regular undirected tree well-known from computer science. This means that it is a collection of n points (called vertices), some of which are connected using n xe2 x80 x89- xe2 x80 x891 line segments (edges) so that each pair of vertices is connected by a path (a sequence of one or more edges). To decipher the prophecy, Heidi needs to perform a number of steps. The first is counting the number of lifelines in the tree xe2 x80 x93 these are paths of length 2, i.e., consisting of two edges. Help her! The first line of the input contains a single integer n xe2 x80 x93 the number of vertices in the tree (1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89n xe2 x80 x89 xe2 x89 xa4 xe2 x80 x8910000). The vertices are labeled with the numbers from 1 to n. Then n xe2 x80 x89- xe2 x80 x891 lines follow, each describing one edge using two space-separated numbers a xe2 x80 x82b xe2 x80 x93 the labels of the vertices connected by the edge (1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89a xe2 x80 x89< xe2 x80 x89b xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89n). It is guaranteed that the input represents a tree. Print one integer xe2 x80 x93 the number of lifelines in the tree. In the second sample, there are four lifelines: paths between vertices 1 and 3, 2 and 4, 2 and 5, and 4 and 5. '...