Islands#1057
The island nation of Isola consists of islands. To facilitate travel between some islands, bridges have been constructed. To ensure no island is overloaded with traffic, each island is connected by at most two bridges. Each bridge allows travel in both directions. To fund the maintenance of bridges and roads, the Isola government has set a toll of one unit for every crossing.
Until recently, Isola did not have a bus service. In response to urgent need, the first bus company "Correira" was established, and it was decided to create bus routes between every pair of islands. However, if there is no route via bridges between two islands, no bus route is established between them.
It was decided that each route operates two trips per day: one in each direction. Naturally, buses will always take the least costly route. "Correira" is interested in knowing how many units per day will be paid for bus crossings over the bridges. Since there are no programmers in the small country of Isola, the company asks you to solve this problem.
The first line contains two integers and (1 \leq n \leq 100\,000; 0 \leq m \leq n) — the number of islands and the number of bridges in Isola. The next lines describe the bridges. Each line contains two integers and (1 \leq x, y \leq n; x \neq y) — the numbers of the islands connected by each bridge. It is guaranteed that each island is connected by at most two bridges.
Output a single integer — the number of units needed for the operation of the bus service.
Beispiel 1