B"Alyona decided to go on a diet and went to the forest to get some apples. There she unexpectedly found a magic rooted tree with root in the vertex 1, every vertex and every edge of which has a number written on. The girl noticed that some of the tree's vertices are sad, so she decided to play with them. Let's call vertex v sad if there is a vertex u in subtree of vertex v such that dist(v, xe2 x80 x89u) xe2 x80 x89> xe2 x80 x89au, where au is the number written on vertex u, dist(v, xe2 x80 x89u) is the sum of the numbers written on the edges on the path from v to u. Leaves of a tree are vertices connected to a single vertex by a single edge, but the root of a tree is a leaf if and only if the tree consists of a single vertex -- root. Thus Alyona decided to remove some of tree leaves until there will be no any sad vertex left in the tree. What is the minimum number of leaves Alyona needs to remove? In the first line of the input integer n (1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89n xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89105) is given -- the number of vertices in the tree. In the second line the sequence of n integers a1, xe2 x80 x89a2, xe2 x80 x89..., xe2 x80 x89an (1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89ai xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89109) is given, where ai is the number written on vertex i. The next n xe2 x80 x89- xe2 x80 x891 lines describe tree edges: ith of them consists of two integers pi and ci (1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89pi xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89n, xe2 x80 x89- xe2 x80 x89109 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89ci xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89109), meaning that there is an edge connecting vertices i xe2 x80 x89+ xe2 x80 x891 and pi with number ci written on it. Print the only integer -- the minimum number of leaves Alyona needs to remove such that there will be no any sad vertex left in the tree. The following image represents possible process of removing leaves from the tree: "...