View Compilation Error

0_0_29173056_26455.cpp:92:12: error: 'p' was not declared in this scope
 double Dis(p a, p b) {
            ^
0_0_29173056_26455.cpp:92:17: error: 'p' was not declared in this scope
 double Dis(p a, p b) {
                 ^
0_0_29173056_26455.cpp:92:20: error: expression list treated as compound expression in initializer [-fpermissive]
 double Dis(p a, p b) {
                    ^
0_0_29173056_26455.cpp:92:22: error: expected ',' or ';' before '{' token
 double Dis(p a, p b) {
                      ^
0_0_29173056_26455.cpp: In function 'int main()':
0_0_29173056_26455.cpp:145:30: error: 'Dis' cannot be used as a function
     double d = Dis(a[i], a[j]);
                              ^