#include <bits/stdc++.h> using namespace std; int p[10001]; vector<vector<int>> a; vector<int> v; void dfs(int u, int k, int cnt){ v[u] = cnt; for(int e : a[u]) if(e != k) dfs(e, u, cnt + 1); } int ml = 1, num = 10000; bool tr = false, t = false, op = false; int send_message(int N, int i, int Pi) { p[i] = Pi; if(i >= N - 40){ if(op) return 3; a.assign(N + 1, {}); v.assign(N + 1, 0); for(int j = 1; j <= N; j++){a[p[j]].push_back(j);} dfs(0, -1, 0); int mx = 1; for(int j = 2; j <= N; j++) if(v[j] > v[mx]) mx = j; if(i > N-40 and mx != ml){ op = true; return 3; } ml = mx; int cnt = 0; if(tr) return 4; int num2 = num; while(mx % 10 == num2 % 10){ mx /= 10; num2 /= 10; cnt++; if(num2 == 1){ tr = true; return 4; } } if(!t){ t = true; return cnt; } t = false; if(mx % 10 - num2 % 10 >= 2){ num2 += pow<int>(10, cnt)*2; return 3; } else{ num2 += pow<int>(10, cnt)*(mx % 10 - num2 % 10); return mx % 10 - num2 % 10; } } return 0; } pair<int, int> longest_path(vector<int> S){ int nm = 10000; for(int i = S.size()-40; i < S.size(); i++){ if(S[i] == 3) return {0, i}; if(S[i] == 4) continue; if(i & 1) nm += pow<int>(10, S[i-1])*S[i]; } return {0, nm-10000}; }