View Compilation Error

0_0_36608598_28689.cpp: In function 'void add_edge(int, int, int)':
0_0_36608598_28689.cpp:15:12: error: 'cnt' was not declared in this scope
     edge[++cnt].nex = head[u];
            ^
0_0_36608598_28689.cpp:15:23: error: 'head' was not declared in this scope
     edge[++cnt].nex = head[u];
                       ^