Language: C++

#include<bits/stdc++.h>
#include<unordered_set>
#include<unordered_map>
#include <iostream>
#include <string>
#include <cmath>
using namespace std;
#define ll long long
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define FOR(i,a,b) for(ll i=(a);i<(b);i++)
#define FORR(i,a,b)for(ll i=(a);i<=(b);i++)
#define repR(i,n) for(ll i=n;i>=0;i--)
#define all(v)(v).begin(),(v).end()
#define rall(v)(v).rbegin(),(v).rend()
#define F first
#define S second
#define pb push_back
#define pu push
#define COUT(x) cout<<(x)<<endl
#define PQ priority_queue<ll>
#define PQR priority_queue<ll,vector<ll>,greater<ll>>
#define YES(n) cout << ((n) ? "YES" : "NO"  ) << endl
#define Yes(n) cout << ((n) ? "Yes" : "No"  ) << endl
#define mp make_pair
#define maxs(x,y) (x = max(x,y))
#define mins(x,y) (x = min(x,y))
#define sz(x) (int)(x).size()
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
const ll MOD = 1000000007LL;
const ll INF = 1LL << 60;
using vll = vector<ll>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vvll = vector<vll>;
using vstr = vector<string>;
using pll = pair<ll, ll>;
using vc = vector<char>;
using vvc = vector<vc>;
ll dx[4]={0,1,0,-1};
ll dy[4]={1,0,-1,0};
int main(){
  ll n;
  cin>>n;
  vvll t(n,vll(0));
  vector<pll> pp(n-1);
  rep(i,n-1){
    ll a,b;
    cin>>a>>b;
    a--;
    b--;
    t[a].pb(b);
    t[b].pb(a);
    pp[i]=mp(a,b);
  }
  map<pll,ll> m;
  queue<ll> que;
  vll cs(n,-1);
  que.pu(0);
  ll k=0;
  while(sz(que)){
    ll v=que.front();
    que.pop();
    k=max(sz(t[k]),k);
    ll cu=1;
    for(ll p:t[v]){
      if(cs[p]!=-1)continue;
      if(cs[v]==cu) cu++;
      cs[p]=m[pll(v,p)]=m[pll(p,v)]=cu;
      cu++;
      queue.pu(p);
    }
  }
  COUT(k);
  rep(i,n-1){
    COUT(m[pp[i]]);
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:64:10: error: no matching function for call to 'max(int, long long int&)'
   64 |     k=max(sz(t[k]),k);
      |       ~~~^~~~~~~~~~~~
In file included from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:64:10: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'long long int')
   64 |     k=max(sz(t[k]),k);
      |       ~~~^~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61:
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:64:10: note:   mismatched types 'std::initializer_list<_Tp>' and 'int'
   64 |     k=max(sz(t[k]),k);
      |       ~~~^~~~~~~~~~~~
a.cc:71:12: error: expected unqualified-id before '.' token
   71 |       queue.pu(p);
      |            ^