View Compilation Error

0_0_21599024_27338.cpp:1:9: error: 'maxn' was not declared in this scope
 int vis[maxn];
         ^
0_0_21599024_27338.cpp: In function 'void init()':
0_0_21599024_27338.cpp:4:12: error: 'vis' was not declared in this scope
     memset(vis, 0, sizeof(vis));
            ^
0_0_21599024_27338.cpp:4:31: error: 'memset' was not declared in this scope
     memset(vis, 0, sizeof(vis));
                               ^
0_0_21599024_27338.cpp:5:15: error: 'maxn' was not declared in this scope
     for(i=1;i<maxn;i++){
               ^
0_0_21599024_27338.cpp:8:15: error: 'maxn' was not declared in this scope
     for(i=2;i<maxn;i++){
               ^