#include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     vector<int> a(n);     map<int, vector<int>> indices;     for (int i = 0; i < n; i++) cin >> a[i], indices[a[i]].push_back(i);     map<int, int> dp;     int mxn = 0, ans = -1;     for (int i = n - 1; i >= 0; i--) {       dp[a[i]] = 1 + dp[a[i] + 1];       if (dp[a[i]] > mxn) mxn = dp[a[i]], ans = a[i];     }     cout << mxn <<   n ;     int prevI = -1, currA = ans;     while (mxn) {       int currI =           lower_bound(indices[currA].begin(), indices[currA].end(), prevI) -           indices[currA].begin();       cout << indices[currA][currI] + 1 <<    ;       prevI = indices[currA][currI], currA++, mxn--;     }     return 0;   }   