View Compilation Error

0_0_20619971_8065.cpp: In function 'int main()':
0_0_20619971_8065.cpp:50:9: error: 'tot' was not declared in this scope
         tot = 0 ;
         ^
0_0_20619971_8065.cpp:55:29: error: 'add_edge' was not declared in this scope
             add_edge( u , v ) ;
                             ^
0_0_20619971_8065.cpp:70:17: error: 'a' was not declared in this scope
                 a[lena++] = pos[u] ;
                 ^
0_0_20619971_8065.cpp:76:32: error: 'modify' was not declared in this scope
                 modify( u , 20 ) ;
                                ^
0_0_20619971_8065.cpp:78:34: error: 'ANS' was not declared in this scope
             printf( "%d\n" , ANS() ) ;
                                  ^