View Compilation Error

0_0_27949038_5730.cpp: In function 'int main()':
0_0_27949038_5730.cpp:44:30: error: 'sort' was not declared in this scope
         sort(yl+1,yl+m+1,cmp1);
                              ^
0_0_27949038_5730.cpp:49:34: error: 'nth_element' was not declared in this scope
             nth_element(a,a+t,a+p);
                                  ^