#include <stdio.h> #define MAX 101 int count = 0; int visits[MAX]; int metrix[MAX][MAX]; void DFS (int v, int N) { visits[v] = 1; for (int i = 1; i <= N; i++) { if (!visits[i] && metrix[v][i]) { count++; DFS(i, N); } } } int main(void) { int N = 0; int E = 0; scanf("%d", &N); scanf("%d", &E); for (int i = 0; i < E; i++) { int firstV, secondV; scanf("%d %d", &firstV, &secondV); metrix[firstV][secondV] = 1; metrix[secondV][firstV] = 1; } DFS(1, N); printf("%d\n", count); return 0; }