Directed Acyclical Graph Crash - c++

Question

So I am having trouble with my code and cant figure out exactly what the problem is. I am supposed to take in a text file, where the first line shows the number of vertices, and the second line shows the number of edges.From this text file I am trying to take in the values shown then build a graph and determine whether or not it contains a cycle. Then display nodes which have no incoming edges.
t1.txt
3
2
1,2,
2,3
I am not sure exactly where I am going wrong here.
t2.txt
5
5
3,4,
4,5,
2,3,
1,3,
3,5
//
#include <iostream>
#include <fstream>
#include <sstream>
#include<string>
#include<list>
#include <limits.h>
#include <stack>
#include<stdlib.h>
#include <cstdlib>
using namespace std;
class Graph
{
int V; // No. of vertices
list<int> *adj; // Pointer to an array containing adjacency lists
bool isCyclicUtil(int v, bool visited[], bool *rs); // used by isCyclic()
public:
Graph(int V); // Constructor
void addEdge(int v, int w); // to add an edge to graph
bool isCyclic(); // returns true if there is a cycle in this graph
};
Graph::Graph(int V)
{
this->V = V;
adj = new list<int>[V];
}
void Graph::addEdge(int v, int w)
{
adj[v].push_back(w); // Add w to v’s list.
}
bool Graph::isCyclicUtil(int v, bool visited[], bool *recStack)
{
if(visited[v] == false)
{
// Mark the current node as visited and part of recursion stack
visited[v] = true;
recStack[v] = true;
// Recur for all the vertices adjacent to this vertex
list<int>::iterator i;
for(i = adj[v].begin(); i != adj[v].end(); ++i)
{
if ( !visited[*i] && isCyclicUtil(*i, visited, recStack) )
return true;
else if (recStack[*i])
return true;
}
}
recStack[v] = false; // remove the vertex from recursion stack
return false;
}
// Returns true if the graph contains a cycle, else false.
bool Graph::isCyclic()
{
// Mark all the vertices as not visited and not part of recursion
// stack
bool *visited = new bool[V];
bool *recStack = new bool[V];
for(int i = 0; i < V; i++)
{
visited[i] = false;
recStack[i] = false;
}
// Call the recursive helper function to detect cycle in different
// DFS trees
for(int i = 0; i < V; i++)
if (isCyclicUtil(i, visited, recStack))
return true;
return false;
}
int main()
{
float n ,n2;
string filename,line;
cout << "Enter filename: ";
cin >> filename;
fstream file;
file.open(filename.c_str());
file >> n;
file >> n2;
int num = n;
cout << num << " ";
int num2 = n2;
cout << num2 << " ";
string matrix[num2][2];
//int ** mat = new int*[num2];
int mat[num2][2];
Graph g(num);
while(!file.eof())
{
for(int i = 0; i < num2; i++)
{
//mat[i] = new int[num];
for(int j = 0; j < 2; j++)
{
if(getline(file,line,','))
{
matrix[i][j] = line; // read file into string matrix
istringstream(line) >> mat[i][j]; //convert to int and store in dynamic 2d array
}
}
}
}
cout << endl << "TEST " << mat[0][0] << " " << mat[0][1] << " " << mat[1][0]<< " " << mat[1][1];
for(int i = 0; i <num2-1; i++)
{
int temp1,temp2;
temp1 = mat[i][0];
temp2 = mat[i][1];
g.addEdge(temp1,temp2);
}
if(g.isCyclic())//Here is where the program crashes for input t2.txt
cout << "Graph is not DAG";
else
cout << "Graph is DAG";
return 0;
}