View Compilation Error

0_0_28586577_5439.cpp: In function 'int main(int, char**)':
0_0_28586577_5439.cpp:31:2: error: incomplete type 'std::ios {aka std::basic_ios<char>}' used in nested name specifier
  ios::sync_with_stdio(false);
  ^
0_0_28586577_5439.cpp:32:2: error: 'cin' was not declared in this scope
  cin.tie(0);
  ^