1 #include<iostream>
 2 #include<algorithm>
 3 using namespace std;
 4 
 5 const int INF = 0x3fffffff;
 6 //當前位置的元素必須滿足，大于等于左邊的最大元素，小于等于右邊的最小元素，才可能是主元
 7 int a[100010] = {0};
 8 int leftMAX[100010] = {0};
 9 int rightMIN[100010] = {0};
10 int ans[100010] = {0},num = 0;
11 int main() {
12     int n;
13     scanf("%d",&n);
14     for(int i = 0; i < n; ++i)
15         scanf("%d",&a[i]);
16     leftMAX[0] = 0;//A[0]左邊沒有比它大的數
17     for(int i = 1; i <= n; ++i)
18         leftMAX[i] = max(leftMAX[i-1],a[i-1]);
19     rightMIN[n-1] = INF;//A[n-1]右邊沒有比它小的數
20     for(int i = n-2; i>= 0; --i)
21         rightMIN[i] = min(rightMIN[i+1],a[i+1]);
22     for(int i = 0; i < n; ++i) {
23         if(a[i] > leftMAX[i] && a[i] < rightMIN[i]) {
24             ans[num++] = a[i];
25         }
26     }
27     printf("%d\n",num);
28     for(int i = 0; i < num; ++i) {
29         if(i > 0) printf(" ");
30         printf("%d",ans[i]);
31     }
32     printf("\n");//不加這句，測試點2無法通過
33     return 0;
34 }