View Compilation Error

0_0_33280435_18947.cpp:1:1: error: 'string' does not name a type
 string str,str_;
 ^
0_0_33280435_18947.cpp:2:2: error: 'cin' does not name a type
  cin>>n;
  ^
0_0_33280435_18947.cpp:3:2: error: expected unqualified-id before 'while'
  while(n--){
  ^