hackerearcth Unreachable Nodes

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define test int t; cin>>t; for(int cs=1;cs<=t;cs++)
bool visit[100005];
vector<ll>graph[100005];

void dfs(ll x)
{
    visit[x]=1;
    for(ll i=0;i<graph[x].size();i++)
    {
        ll nx=graph[x][i];
        if(visit[nx]==0)
        {
            dfs(nx);
        }
    }
}

int main()
{
   ios_base::sync_with_stdio(0);
   cin.tie(0);cout.tie(0);

   ll n,m,x,a,c,d,e=0,i,j,k,l;
   cin>>n>>m;

   for(i=0;i<m;i++)
   {
       cin>>a>>c;
       graph[a].push_back(c);
       graph[c].push_back(a);
   }
   cin>>x;
   dfs(x);
   for(i=1;i<=n;i++)
   {
       if(visit[i]==0)
       {
           e++;
       }
   }
   cout<<e<<endl;
   return 0;
}