View Compilation Error

0_0_36065967_11534.cpp: In function 'int main()':
0_0_36065967_11534.cpp:12:26: error: 'sort' was not declared in this scope
 sort(pos + 1, pos + N + 1);
                          ^
0_0_36065967_11534.cpp:13:29: error: 'ceil' was not declared in this scope
 med = int(ceil(double(N) / 2));
                             ^