Language: C++

#include <iostream>
#include <vector>
#include <tuple>
#include <deque>
#include <set>
#include <map>
#include <cmath>
#include <string>
#include <algorithm>
#include <unordered_set>
#define int long long
#define all(x) (x).begin(), (x).end()
#define allr(x) (x).rbegin(), (x).rend()

using namespace std;

const int MOD = 1e9 + 7;
const int INF = 1e9;

void fast()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
}


vector <vector <int> > g;
vector <int> d;
int dfs(int v, int dst = 0)
{
    d[v] = dst;
    for (int e : g[v])
    {
        dfs(e, dst + 1);
    }
}

signed main()
{
	fast();
    int n;
    cin >> n;
    g.resize(n);
    d.resize(n);
    for (int i = 1; i < n; ++i)
    {
        int a;
        cin >> a;
        g[a - 1].push_back(i);
    }
    dfs(0);
    int mx = 0;
    for (int i = 0; i < n; ++i)
    {
        mx = max(mx, d[i] + g[i].size());
    }
    cout << mx << '\n';
    return 0;
}


Compiler output:
a.cc: In function 'long long int dfs(long long int, long long int)':
a.cc:37:1: warning: no return statement in function returning non-void [-Wreturn-type]
   37 | }
      | ^
a.cc: In function 'int main()':
a.cc:56:17: error: no matching function for call to 'max(long long int&, long long unsigned int)'
   56 |         mx = max(mx, d[i] + g[i].size());
      |              ~~~^~~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/string:51,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 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:56:17: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'long long unsigned int')
   56 |         mx = max(mx, d[i] + g[i].size());
      |              ~~~^~~~~~~~~~~~~~~~~~~~~~~~
/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,
                 from a.cc:9:
/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:56:17: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
   56 |         mx = max(mx, d[i] + g[i].size());
      |              ~~~^~~~~~~~~~~~~~~~~~~~~~~~