View Compilation Error

0_0_20966205_8258.cpp: In function 'void init()':
0_0_20966205_8258.cpp:3:12: error: 'sg' was not declared in this scope
     memset(sg,0,sizeof(sg));
            ^
0_0_20966205_8258.cpp:3:27: error: 'memset' was not declared in this scope
     memset(sg,0,sizeof(sg));
                           ^
0_0_20966205_8258.cpp:7:25: error: 'maxn' was not declared in this scope
     for(int i = 1 ; i < maxn;i++)
                         ^
0_0_20966205_8258.cpp:9:16: error: 'vis' was not declared in this scope
         memset(vis,0,sizeof(vis));
                ^
0_0_20966205_8258.cpp:27:12: error: 'cout' was not declared in this scope
            cout<<"i:"<<i<<" sg[i]"<<sg[i]<<endl;
            ^
0_0_20966205_8258.cpp:27:44: error: 'endl' was not declared in this scope
            cout<<"i:"<<i<<" sg[i]"<<sg[i]<<endl;
                                            ^