#include <bits/stdc++.h>   #pragma comment(linker,  /STACK:102400000,102400000 )   #pragma GCC optimize( Ofast )   #pragma GCC target( sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native )   using namespace std;   const int maxn = 2e5 + 5;   map<int, int> dp, pos;   int pre[maxn];   int main() {     ios::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);     int i, j, k, m, n;     cin >> n;     for (int i = 1; i <= n; ++i) {       cin >> k;       if (!dp.count(k - 1)) {         dp[k] = 1;         pre[i] = -1;         pos[k] = i;       } else if (dp[k - 1] + 1 > dp[k]) {         dp[k] = dp[k - 1] + 1;         pos[k] = i;         pre[i] = pos[k - 1];       }     }     pair<int, int> mst = {0, 0};     for (auto it : dp) {       if (it.second > mst.second) {         mst.first = it.first;         mst.second = it.second;       }     }     int npos = pos[mst.first];     vector<int> ans;     while (npos != -1) {       ans.push_back(npos);       npos = pre[npos];     }     reverse(ans.begin(), ans.end());     cout << ans.size() << endl;     for (auto it : ans) cout << it <<    ;     return 0;   }   