vector graph[100001];
          bool visited[100001];
          
          //DFS traversal function of graph
          /*time complexity = O(n+m)
           where,n = no of vertices and m = no of edges
           -->Stack data structure is used
          */
          void dfs(int s)
          {
              if (visited[s])
                  return;
          
              visited[s] = true;
              cout << s << " ";
              for (int i = 0; i < graph[s].size(); ++i)
              {
                  if (visited[graph[s][i]] == false)
                      dfs(graph[s][i]);
              }
          }