2606번

2606번

#include <iostream>
#include <vector>
using namespace std;

vector<int> computers[101];
vector<bool> visit(101);
int cnt = 0;

void dfs(int start) {
	visit[start] = true;
	for (int i = 0;i < computers[start].size();i++) {
		int visitedComputer = computers[start][i];
		if(!visit[visitedComputer]) {
			visit[visitedComputer] = true;
			cnt++;
			dfs(visitedComputer);
		}
	}
}

int main() {
	int n, pairs, point1, point2;
	cin >> n >> pairs;

	for (int i = 0;i < pairs;i++) {
		cin >> point1 >> point2;
		computers[point1].push_back(point2);
		computers[point2].push_back(point1);
	}
	dfs(1);

	cout << cnt;
}