#define _CRT_SECURE_NO_WARNINGS
#include "bits/stdc++.h"
using namespace std;
#define all(a) a.begin(), a.end()
constexpr int N = 202;
const int inf = 202;
short pred[N][N] = {};
bitset<N> dp[N];
vector<short> a;
void dfs(short l, short r) {
    if (l + 2 == r) {
        cout << l + 2 << '\n';
        return;
    }
    short cntr = pred[l][r];
    if (cntr - 1 >= l + 1) {
        dfs(l, cntr);
    }
    if (cntr + 1 <= r - 1) {
        dfs(cntr, r);
    }
    cout << cntr + 1 << '\n';
}
signed main() {
#ifdef _DEBUG
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    short n; cin >> n;
    a.resize(n);
    for (short i = 0; i < n; i++) {
        cin >> a[i];
    }
    for (short i = 1; i + 1 < n; i++) {
        if (a[i - 1] > a[i] && a[i] < a[i + 1] || a[i - 1] < a[i] && a[i + 1] < a[i]) {
            dp[i][i] = true;
            pred[i - 1][i + 1] = i;
        }
    }
    for (short len = 2; len < n; len++) {
        for (short l = 0; l + len < n; l++) {
            short r = l + len;
            for (short centr = l + 1; centr <= r - 1; centr++) {
                bool dp1 = (centr - 1 >= l + 1 ? dp[l + 1][centr - 1] : 1);
                bool dp2 = (centr + 1 <= r - 1 ? dp[centr + 1][r - 1] : 1);
                if ((a[centr] > a[l] && a[centr] > a[r] ||
                    a[centr] < a[l] && a[centr] < a[r]
                    ) && dp1 && dp2) {
                    pred[l][r] = centr;
                    dp[l + 1][r - 1] = 1;
                    break;
                }
            }
        }
    }
    vector<short> dpmin(n + 1, inf), p(n + 1, -1);
    dpmin[1] = 0;
    p[1] = 1;
    for (short i = 2; i <= n; i++) {
        for (short j = 1; j < i; j++) {
            if (dpmin[j] == inf) { continue; }
            short l = j + 1, r = i - 1;
            bool dp1 = (l <= r ? dp[l - 1][r - 1] : 1);
            if (dp1 && a[i - 1] >= a[j - 1] && dpmin[i] > dpmin[j] + (l <= r ? r - l + 1 : 0)) {
                dpmin[i] = dpmin[j] + (l <= r ? r - l + 1 : 0);
                p[i] = j;
            }
        }
    }
    if (dpmin[n] == inf) {
        cout << -1;
        return 0;
    }
    cout << dpmin[n] << '\n';
    for (short v = n; v != p[v]; v = p[v]) {
        if (v - p[v] - 1 > 0) {
            dfs(p[v] - 1, v - 1);
        }
    }
}