A farm has n irrigation zones numbered 1 through n. Some pairs of zones are joined by a bidirectional water pipe. Two zones belong to the same cluster if water can travel between them through one or more pipes. A zone with no pipes forms a cluster by itself.
Report how many clusters there are.
Input format
Line 1: two integers n and m, the number of zones and the number of pipes.
Next m lines: two integers u and v each, meaning a pipe joins zone u and zone v. A pipe may be listed more than once; a pipe never joins a zone to itself.
Output format
A single integer: the number of clusters.
Constraints
- 1 <= n <= 100000
- 0 <= m <= 200000
- 1 <= u, v <= n and u != v