IARCS Problem

http://opc.iarcs.org.in/index.php/problems/TASKFORCE is the problem I've been working on for so many hours, yet no luck. Please Help!!

#include <iostream>
using namespace std;

int edg(int);
int k=0,m=0,n=0;
int graph[4000][4000];
int edges[4000];

int main() 
{
    cin>>n>>m>>k;
    int t1,t2;
    for(int i=0;i<4000;i++) 
    {
        edges[i]=-1;
        for(int j=0;j<4000;j++)
        {
            graph[i][j]=0;
        }
    }
    for(int i=1;i<=m;i++)
    {
        cin>>t1>>t2;
        graph[t1][t2]=1;
        graph[t2][t1]=1;
    }
    for(int i=1;i<=n;i++)
    {
        edges[i] = edg(i);      //Contains actual edges for vertex I which contribute to k
    } //actual edges means nodes which themselves have >=k edges and can be used in the force
    int size = 0;
    for(int i=1;i<=n;i++)
    {
        if(edges[i]>=k)
        {
            size++;
        }
    }
    if(size>0)
    {
        cout<<"YES"<<endl<<size;
    }else
    cout<<"NO";
}

int edg(int i)
{
    if(edges[i]==-1)
    {
        edges[i]=0;
        int a = 0;
        for(int j=1;j<=n;j++)
        {   
            if(graph[i][j]==1&&edges[j]!=-1)
            {
                if(edges[j]>=k)
                a++;
            }
            if(graph[i][j]==1&&edges[j]==-1)
            {
                int t = edg(j);
                if(t>=k)
                a++;
            }

        }

        return a;
    }
    else
    return edges[i];
}