View Compilation Error

0_0_29950980_19260.cpp: In function 'int main()':
0_0_29950980_19260.cpp:69:23: error: 'sort' was not declared in this scope
         sort(b+1,b+1+n);
                       ^
0_0_29950980_19260.cpp:70:28: error: 'unique' was not declared in this scope
         *b=unique(b+1,b+1+n)-b-1;
                            ^
0_0_29950980_19260.cpp:73:20: error: 'reverse' was not declared in this scope
   reverse(a+1,a+1+n);
                    ^