Doubt regarding solution (SS4)

I am unable to figure out why i am getting WA although my solution seems to be correct.
Here is the problem link:https://www.codechef.com/ENOC2019/problems/SS4

And this is my solution:
#include <bits/stdc++.h>
#include <boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;
using namespace std;
#define int long long
#define ld long double
#define nl ‘\n’
#define pb push_back
#define f(i,n) for(int i=0;i<n;i++)
#define Fast ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
const int M =1e9+7;

void solve()
{
int n;
cin>>n;
vector<vector> v(n+1);
for(int i=1;i<=n-1;i++)
{
int x,y;
cin>>x>>y;
v[x].pb(y);
}
/for(int i=1;i<=n;i++)
{
for(int j=0;j<v[i].size();j++)
{
cout<<v[i][j]<<" ";
}
cout<<nl;
}
/
int max=1,d=1,s=0,x=1,j=0,k=1;

   for(int i=1;i<=n;i++)
   { 
       s+=v[i].size();
       j++;
       if(j==x)
       {  //cout<<max<<" ";
           d++;
           if(s>max)
           {
               max=s;
               k=d;
           }
           x=s;
           s=0;
           j=0;
       }
       
   }
   cout<<k<<nl;

}
signed main()
{
Fast;
solve();

return 0;
}
PLEASE look into it.

It would be better if you can explain your approach rather than sharing the code.
The correct approach was to find the level of the tree having max nodes.

@sandeep1103
Hey! When are you guys planning to publish the editorial for the questions of ENOC2019?

soon enough.