View Compilation Error

0_0_38344187_31767.cpp: In function 'long long int dfs(long long int, long long int, long long int)':
0_0_38344187_31767.cpp:47:42: error: 'sum' was not declared in this scope
     if(fl = (k & 4 && a && !up && lft == sum + 3)) t |= 4;
                                          ^