View Compilation Error

0_0_24956244_4036.cpp: In function 'void cac(int, int, int)':
0_0_24956244_4036.cpp:97:32: error: 'sort' was not declared in this scope
     sort(buf.begin(), buf.end());
                                ^
0_0_24956244_4036.cpp: In function 'int main()':
0_0_24956244_4036.cpp:127:53: error: 'max_element' was not declared in this scope
         if (*max_element(has_market+1,has_market+1+n) == 0) {
                                                     ^
0_0_24956244_4036.cpp:133:50: error: 'max_element' was not declared in this scope
         printf("%d\n", *max_element(ans+1,ans+1+n));
                                                  ^