#include<iostream.h>
int main()
{
    int n,i,j,k[7165],l,**a,b[7165],kol=0;
    cin>>n;
        a=new int *[n+1];
for(i=1;i<=n;i++)
a[i]=new int[n+1];
for(i=1;i<=n;i++)
for(j=1;j<=n;j++)
a[i][j]=0;
for(i=1;i<=n;i++)
{
    cin>>k[i];
    for(j=0;j<k[i];j++)
    {
        cin>>l;
        a[i][l]=1;
    }
}
for(i=1;i<=n;i++)
{
    if(k[i]>1)
    {
    b[kol++]=i;
        for(j=i+1;j<=n;j++)
            if(a[j][i]==1)
            {
                a[j][i]=0;
                k[j]--;
            }
    }
}

cout<<kol<<endl;
if(kol!=0){
for(i=0;i<kol;i++)
cout<<b[i]<<" ";}
return 0;
}
Thank in advance!!!!!!

Try this:
4
1 3
2 3 4
3 1 2 4
2 2 3
Your output:
2
2 3
This answer is wrong.
"If the groups are of the same size then you are to describe the group that contains the child number one"
So possible answer is:
2
1 4