View Compilation Error

0_0_31459133_6129.cpp:5:12: error: array bound is not an integer constant before ']' token
 int dp[maxn][maxn];
            ^
0_0_31459133_6129.cpp:5:18: error: array bound is not an integer constant before ']' token
 int dp[maxn][maxn];
                  ^
0_0_31459133_6129.cpp:6:11: error: array bound is not an integer constant before ']' token
 int a[maxn];
           ^
0_0_31459133_6129.cpp: In function 'int main()':
0_0_31459133_6129.cpp:13:5: error: 'dp' was not declared in this scope
     dp[i][j] = f;
     ^
0_0_31459133_6129.cpp:17:11: error: 'a' was not declared in this scope
    cin >> a[i];
           ^
0_0_31459133_6129.cpp:19:8: error: 'a' was not declared in this scope
   sort(a+1,a+n+1);
        ^
0_0_31459133_6129.cpp:20:3: error: 'dp' was not declared in this scope
   dp[0][0] = 0;
   ^