View Compilation Error

0_0_14701120_27469.cpp: In function 'double lala(int, int)':
0_0_14701120_27469.cpp:43:26: error: 'sort' was not declared in this scope
     sort(QWQ,QWQ+num,cmdy);
                          ^
0_0_14701120_27469.cpp: In function 'int main()':
0_0_14701120_27469.cpp:61:29: error: 'sort' was not declared in this scope
         sort(hehe,hehe+n,cmd);
                             ^