How can I to modify a program

// GeeksforGeeks.com
// C# program to calculate   cycles of 
// length n in a given graph
 
using System; 
  
class GFG  
{ 
      
    // Number of vertices 
    public static int V = 5; 
    static int count = 0; 
      
    static void DFS(int [,]graph, bool []marked, 
                    int n, int vert, int start)  
    { 
          
        // mark the vertex vert as visited 
        marked[vert] = true; 
          
        // if the path of length (n-1) is found 
        if (n == 0)  
        { 
              
            // mark vert as un-visited to  
            // make it usable again 
            marked[vert] = false; 
              
            // Check if vertex vert end  
            // with vertex start 
            if (graph[vert, start] == 1) 
            { 
                count++; 
                return; 
            }  
            else
                return; 
        } 
          
        // For searching every possible  
        // path of length (n-1) 
        for (int i = 0; i < V; i++) 
            if (!marked[i] && graph[vert, i] == 1) 
              
                // DFS for searching path by 
                // decreasing length by 1 
                DFS(graph, marked, n - 1, i, start); 
          
        // marking vert as unvisited to make it 
        // usable again 
        marked[vert] = false; 
    } 
      
    // Count cycles of length N in an  
    // undirected and connected graph. 
    static int countCycles(int [,]graph, int n)  
    { 
          
        // all vertex are marked un-visited 
        // initially. 
        bool []marked = new bool[V]; 
          
        // Searching for cycle by using  
        // v-n+1 vertices 
        for (int i = 0; i < V - (n - 1); i++)  
        { 
            DFS(graph, marked, n - 1, i, i); 
              
            // ith vertex is marked as visited 
            // and will not be visited again 
            marked[i] = true; 
        } 
          
        return count / 2;  
    } 
      
    // Driver code 
    public static void Main() 
    { 
        int [,]graph = {{0, 1, 0, 1, 0}, 
                        {1, 0, 1, 0, 1}, 
                        {0, 1, 0, 1, 0}, 
                        {1, 0, 1, 0, 1}, 
                        {0, 1, 0, 1, 0}}; 
          
        int n = 4; 
          
        Console.WriteLine("Total cycles of length "+ 
                        n + " are "+  
                        countCycles(graph, n)); 
    } 
}