WA in Is it a tree problem

[bpradeep_sof]

spoj.pl/problems/PT07Y/
can anybody tell why am i getting wrong answer for this code? It is working correctly for all test cases in my pc.

#include<iostream>
using namespace std;
main()
{
    int n,e,i,j,k,m;
    while((scanf("%d",&n))!=EOF)
    {
        scanf("%d",&e);
        if(e == n-1 && e>0)
        {
            bool arr[n+1][n+1],visited[n+1],connected=1;
            memset(visited,0,sizeof(visited));
            int stack[2*n];
            for(k=0;k<e;k++)
            {
                scanf("%d%d",&i,&j);
                arr[i][j]=arr[j][i]=true;
            }
            int top = -1;
            stack[++top] = i;
            visited[i] = true;
            bool found = 0;
            while(top > -1)
            {
                found = 0;
                for(m=1; m<n+1; m++)
                {
                    if(arr[stack[top]][m] == 1 && visited[m] != true)
                    {
                        stack[++top]=m;
                        visited[m] = true;
                        found = true;
                        break;
                    }
                }
                if(!found)
                top--;
            }
            for(m=1;m<n+1;m++)
            {
                if(visited[m] == false)
                {
                    connected=0;
                    break;
                }
            }
            if(connected)
        cout<<"YES\n";
        else
        cout<<"NO\n";
    }
    else
    cout<<"NO\n";
}
}

Thanks in advance.

[leppyr64]

You are leaving orphaned data in the input stream. Just because you know the answer is going to be "NO", doesn't mean you don't have to take the input.