View Compilation Error

0_0_21446402_27584.cpp: In constructor 'edge::edge(int, int)':
0_0_21446402_27584.cpp:12:28: error: '_v' was not declared in this scope
     edge(int v, int w) : v(_v), w(_w){}  
                            ^
0_0_21446402_27584.cpp:12:35: error: '_w' was not declared in this scope
     edge(int v, int w) : v(_v), w(_w){}  
                                   ^