View Compilation Error

0_0_18345090_13356.cpp:8:11: error: size of array 'a' is not an integral constant-expression
 int a[MAXN], b[MAXN];
           ^
0_0_18345090_13356.cpp:8:20: error: size of array 'b' is not an integral constant-expression
 int a[MAXN], b[MAXN];
                    ^