View Compilation Error

0_0_19206187_13315.cpp: In member function 'void LCA::init()':
0_0_19206187_13315.cpp:40:20: error: 'mem' was not declared in this scope
         mem(head,-1);
                    ^
0_0_19206187_13315.cpp: In function 'int main()':
0_0_19206187_13315.cpp:128:30: error: 'mem' was not declared in this scope
         int sun = 0;mem(vis,0);
                              ^