View Compilation Error

0_0_36102577_5100.cpp: In function 'int main()':
0_0_36102577_5100.cpp:21:31: error: 'cin' was not declared in this scope
  ios::sync_with_stdio(false); cin.tie(0);
                               ^
0_0_36102577_5100.cpp:45:25: error: 'sort' was not declared in this scope
    sort(a + l - 1, a + r);
                         ^