B'You are given a tree consisting of n vertices, and q triples (x_i, y_i, s_i) , where x_i and y_i are integers from 1 to n , and s_i is a string with length equal to the number of vertices on the simple path from x_i to y_i . You want to write a lowercase Latin letter on each vertex in such a way that, for each of q given triples, at least one of the following conditions holds: Find any possible way to write a letter on each vertex to meet these constraints, or report that it is impossible. The first line contains two integers n and q ( 2 <= n <= 4 cdot 10^5 ; 1 <= q <= 4 cdot 10^5 ) -- the number of vertices in the tree and the number of triples, respectively. Then n - 1 lines follow; the i -th of them contains two integers u_i and v_i ( 1 <= u_i, v_i <= n ; u_i ne v_i ) -- the endpoints of the i -th edge. These edges form a tree. Then q lines follow; the j -th of them contains two integers x_j and y_j , and a string s_j consisting of lowercase Latin letters. The length of s_j is equal to the number of vertices on the simple path between x_j and y_j . Additional constraint on the input: sum limits_{j=1}^{q} |s_j| <= 4 cdot 10^5 . If there is no way to meet the conditions on all triples, print NO. Otherwise, print YES in the first line, and a string of n lowercase Latin letters in the second line; the i -th character of the string should be the letter you write on the i -th vertex. If there are multiple answers, print any of them. '...