F

#include <bits/stdc++.h>


using namespace std;

//#define int long long

const long long INF = 1e9 + 7;
const int MAXN = 200 + 10;
const int N = 1e5 + 10;

int last[MAXN][MAXN], rem[MAXN][MAXN];
vector<int> ans;

void get_ans(int l, int r, bool flag = false) {
    if (!flag) {
        if (last[l][r] == l) {
            get_ans(l, r, true);
            return;
        }
        get_ans(l, last[l][r], flag);
        get_ans(last[l][r], r, flag);
    } else {
        if (rem[l][r] == l) {
            return;
        }
        get_ans(l, rem[l][r], flag);
        get_ans(rem[l][r], r, flag);
        ans.emplace_back(rem[l][r] + 1);
    }
}

void solve() {
    int n;
    cin >> n;
    vector<int> a(n);
    for (int i = 0; i < n; ++i) {
        cin >> a[i];
    }
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) {
            rem[i][j] = INF;
        }
    }
    for (int i = 0; i + 1 < n; ++i) {
        rem[i][i + 1] = i;
    }
    for (int len = 3; len <= n; ++len) {
        for (int l = 0; l + len - 1 < n; ++l) {
            int r = l + len - 1;
            for (int m = l + 1; m < r; ++m) {
                if (rem[l][m] != INF && rem[m][r] != INF) {
                    if (a[m] > a[l] && a[m] > a[r] || a[m] < a[l] && a[m] < a[r]) {
                        rem[l][r] = m;
                    }
                }
            }
        }
    }

    int dp[n][n];

    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) {
            dp[i][j] = INF;
            last[i][j] = INF;
        }
    }

    for (int len = 2; len <= n; ++len) {
        for (int l = 0; l + len - 1 < n; ++l) {
            int r = l + len - 1;
            if (a[l] > a[r]) {
                continue;
            }
            if (rem[l][r] != INF) {
                dp[l][r] = len - 2;
                last[l][r] = l;
            }

            for (int m = l + 1; m < r; ++m) {
                if (a[m] < a[l] || a[m] > a[r]) {
                    continue;
                }
                if (dp[l][r] > dp[l][m] + dp[m][r]) {
                    dp[l][r] = dp[l][m] + dp[m][r];
                    last[l][r] = m;
                }
            }
        }
    }
    if (last[0][n - 1] == INF) {
        cout << -1 << '\n';
    } else {
        get_ans(0, n - 1, false);
        cout << ans.size() << '\n';
        for (auto& i: ans) {
            cout << i << '\n';
        }
    }
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    int tt = 1;
//    cin >> tt;
    while (tt--) {
        solve();
    }
}