//#include <iostream>
//#include <string>
//#include <algorithm>
//#include <vector>
#include <bits/stdc++.h>
using namespace std;
int main() {
int n;
cin >> n;
// string op;
// op = "";
// unsigned int h;
// h = 0;
unsigned int x[n];
vector<unsigned int> a;
vector<int> op;
for(int i = 0; i < n; i++) {
int o;
cin >> o;
a.push_back(o);
x[o - 1] = i;
}
for(unsigned int i = n; i > 1; i--) {
for(unsigned int j = x[i - 1]; j >= 0; j--) {
// j = min(j, a.size() - 1);
if(j >= a.size()) {
j = a.size();
}
if(a[j] == i) {
if(j == i - 1) {
break;
}
if(j + 1 > 1) {
op.push_back(j + 1);
h++;
}
if(i > 1) {
op.push_back(i);
h++;
}
if(i - 1 > 1) {
op.push_back(i - 1);
h++;
}
if(j > 1) {
op.push_back(j);
h++;
}
a.erase(a.begin() + j);
break;
}
}
}
cout << op.size();
cout << "\n";
// for(int i = 0; i < op.size(); i++) {
// cout << op[i];
// cout << " ";
// }
for(int z : op)
cout << z << " ";
cout << "\n";
return 0;
}