View Compilation Error

0_0_21809999_13993.cpp:20:11: error: 'edge' was not declared in this scope
 bool cmp2(edge a,edge b)
           ^
0_0_21809999_13993.cpp:20:18: error: 'edge' was not declared in this scope
 bool cmp2(edge a,edge b)
                  ^
0_0_21809999_13993.cpp:20:24: error: expression list treated as compound expression in initializer [-fpermissive]
 bool cmp2(edge a,edge b)
                        ^
0_0_21809999_13993.cpp:21:1: error: expected ',' or ';' before '{' token
 {
 ^