Components After Merges

A network has n devices labeled 1 through n. Initially every device is isolated. You then apply m merge operations one at a time; each operation names two devices and places them (and everything already grouped with either of them) into the same group. A device may be merged with itself, and the same pair may be merged more than once — such operations simply have no effect. After all merges, report how many distinct groups (connected components) remain.

Input format

• Line 1: two integers n and m — the number of devices and the number of merge operations.
• The next m lines: each contains two integers u and v (1-indexed) — merge the groups containing u and v.

Output format

A single integer: the number of connected components after all merges.

Constraints

• 1 ≤ n ≤ 200000
• 0 ≤ m ≤ 200000
• 1 ≤ u, v ≤ n