View Compilation Error

0_0_17451178_8560.cpp:12:16: error: expected unqualified-id before ',' token
 int head[maxn],,du[maxn],vis[maxn];
                ^
0_0_17451178_8560.cpp: In function 'int main()':
0_0_17451178_8560.cpp:42:21: error: 'mem' was not declared in this scope
         mem(head, -1);
                     ^