#include <bits/stdc++.h>   using namespace std;   const long long INF = (long long)1e16;   const int N = 900300;   const int K = 40;   int n;   long long a[N];   long long sum[N];   long long dp[N][2];   int par[N][2][3];   int intPoint[N];   int m;   vector<int> ans;   long long getCost(int L, int R, int f1, int f2) {     int len = R - L;     if (len == 1) {       if (a[L] == 0) return 0;       if (f1 == 0 || f2 == 0) return -1;       return a[L];     }     if (len == 2) {       if (a[L] == a[L + 1]) return 0;       if (a[L] < a[L + 1]) {         if (f2 == 0) return -1;         return abs(a[L + 1] - a[L]);       } else {         if (f1 == 0) return -1;         return abs(a[L + 1] - a[L]);       }     }     if (f1 == 0 && a[L] > a[L + 1]) return -1;     if (f2 == 0 && a[R - 1] > a[R - 2]) return -1;     long long cost = abs(sum[R] - sum[L]);     if (len == 3) {       if (a[L] + a[L + 2] <= a[L + 1]) return cost;       if (f1 == 1 && f2 == 1) return cost;       if (f1 == 0 && f2 == 0) return -1;       return cost;     }     return cost;   }   void restoreAns(int L, int R, int f1, int f2) {     int len = R - L;     if (len == 1) {       return;     }     if (len == 2) {       if (a[L] == 0 || a[L + 1] == 0) return;       ans.push_back(L);       return;     }     if (f1 == 0 && a[L] != 0 && a[L + 1] != 0) {       long long x = min(a[L], a[L + 1]);       ans.push_back(L);       a[L] -= x;       a[L + 1] -= x;     }     if (f2 == 0 && a[R - 1] != 0 && a[R - 2] != 0) {       long long x = min(a[R - 1], a[R - 2]);       ans.push_back(R - 2);       a[R - 2] -= x;       a[R - 1] -= x;     }     for (int i = L; i < R - 1; i++) {       if (a[i] != 0 && a[i + 1] != 0) {         long long x = min(a[i], a[i + 1]);         ans.push_back(i);         a[i] -= x;         a[i + 1] -= x;       }     }   }   int main() {     scanf( %d , &n);     for (int i = 0; i < n; i++) {       scanf( %lld , &a[i]);       sum[i + 1] = sum[i];       if (i % 2 == 0)         sum[i + 1] += a[i];       else         sum[i + 1] -= a[i];     }     for (int i = 0; i <= n; i++) {       if (i < 5 || i > n - 5) {         intPoint[m++] = i;         continue;       }       if (a[i - 1] <= a[i - 2] || a[i] <= a[i + 1]) intPoint[m++] = i;     }     for (int i = 0; i <= m; i++) dp[i][0] = dp[i][1] = -INF;     dp[0][0] = 0;     dp[0][1] = 0;     for (int i = 0; i < m; i++)       for (int f1 = 0; f1 < 2; f1++) {         if (dp[i][f1] < 0) continue;         for (int j = i + 1; j < min(m, i + K); j++) {           for (int f2 = 0; f2 < 2 - f1; f2++)             for (int f3 = 0; f3 < 2; f3++) {               long long cost = getCost(intPoint[i], intPoint[j], f2, f3);               if (cost == -1) continue;               if (dp[i][f1] + cost > dp[j][f3]) {                 dp[j][f3] = dp[i][f1] + cost;                 par[j][f3][0] = i;                 par[j][f3][1] = f1;                 par[j][f3][2] = f2;               }             }         }       }     int x = m - 1;     int f = 0;     if (dp[x][1] > dp[x][0]) f = 1;     while (x > 0) {       restoreAns(intPoint[par[x][f][0]], intPoint[x], par[x][f][2], f);       int nx = par[x][f][0];       f = par[x][f][1];       x = nx;     }     printf( %d n , (int)ans.size());     for (int y : ans) printf( %d n , 1 + y);     return 0;   }