View Compilation Error

0_0_27686073_6002.cpp:6:25: error: array bound is not an integer constant before ']' token
 int a[50+5], pos[maxn<<1];
                         ^
0_0_27686073_6002.cpp: In function 'int main()':
0_0_27686073_6002.cpp:13:13: error: 'pos' was not declared in this scope
             pos[a[i]] = i;
             ^
0_0_27686073_6002.cpp:19:16: error: 'pos' was not declared in this scope
             if(pos[l] > pos[a[i]]) {
                ^