#include <bits/stdc++.h>
using namespace std;
const int maxn = 3e5 + 10, mod = 1e9 + 7;
const long long inf = 1e18;
template <typename A, typename B>
ostream& operator<<(ostream& out, pair<A, B> p) {
  out << "{ " << p.first << ", " << p.second << " }";
  return out;
}
template <typename T>
ostream& operator<<(ostream& out, vector<T> v) {
  out << "[ ";
  for (int i = 0; i < int((v).size()); i++) {
    out << v[i];
    if (i != int((v).size()) - 1) out << " ,";
  }
  out << " ]";
  return out;
}
int a[maxn], dpp[maxn];
long long dp[maxn];
bool is[maxn];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie();
  int n;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  dp[1] = a[1];
  dp[2] = a[2];
  for (int i = 3; i <= n; i++) {
    dp[i] = min(max(a[i], a[i - 1]) + dp[i - 3], a[i] + dp[i - 2]);
    if (dp[i] == dp[i - 3] + max(a[i], a[i - 1]))
      dpp[i] = 2;
    else
      dpp[i] = 1;
  }
  vector<int> vec, ans;
  int tmp = dp[n] < dp[n - 1] ? n : (n - 1);
  while (tmp > 2) {
    if (dpp[tmp] == 2) {
      is[tmp - 1] = 1;
      tmp -= 3;
    } else {
      tmp -= 2;
    }
  }
  for (int i = 1; i <= n; i++) {
    if (is[i]) vec.push_back(i);
  }
  for (int i = 1; i < n; i++) {
    if (is[i] == 0) vec.push_back(i);
  }
  for (int pos : vec) {
    int mn = min(a[pos], a[pos + 1]);
    if (mn != 0) {
      ans.push_back(pos);
      a[pos] -= mn, a[pos + 1] -= mn;
    }
  }
  cout << int((ans).size()) << "\n";
  for (int pos : ans) {
    cout << pos << "\n";
  }
  return 0;
}
