B'This is an unusual problem in an unusual contest, here is the announcement: http://codeforces.com/blog/entry/73543 Find the distance between vertices 1 and n in an undirected weighted graph. The first line contains two integers n, m ( 1 <= q n, m <= q 2 cdot 10^5 ) -- the number of vertices and the number of edges. Each of the next m lines contain description of an edge a_i~b_i~cost_i ( 1 <= q a_i, b_i <= q n , 1 <= q cost_i <= q 10^9 ). Loops and multiple edges? Hmm, why not? Print one integer -- the answer to the problem. If there is no path, print -1 instead. '...