Cod sursa(job #547374)
#include <cstdio>
#include <vector>
using namespace std;
vector <int> a[100005];
int n,m,viz[100005],h,x,y,ok,i;
void DFS(int nod)
{
int j;
viz[nod] = 1;
for (j=0;j<a[nod].size();j++)
if (!viz[a[nod][j]]) DFS(a[nod][j]);
}
int main()
{
freopen("dfs.in","r",stdin);
freopen("dfs.out","w",stdout);
scanf("%d %d",&n,&m);
for (i=1;i<=m;i++)
{
scanf("%d %d",&x,&y);
a[x].push_back(y);
a[y].push_back(x);
}
for (i=1;i<=n;i++) if (!viz[i]) {
h++;
DFS(i);
}
printf("%d\n",h);
return 0;
}