View Compilation Error

0_0_18589768_6008.cpp: In function 'float dist(int, int, point*)':
0_0_18589768_6008.cpp:68:22: error: 'sort' was not declared in this scope
     sort(c, c+p, cmpy);
                      ^
0_0_18589768_6008.cpp: In function 'int main()':
0_0_18589768_6008.cpp:98:30: error: 'sort' was not declared in this scope
         sort(a, a + num, cmpx);
                              ^