View Compilation Error

0_0_25992635_10844.cpp: In function 'int main()':
0_0_25992635_10844.cpp:9:2: error: incomplete type 'std::ios {aka std::basic_ios<char>}' used in nested name specifier
  std::ios::sync_with_stdio(false);
  ^
0_0_25992635_10844.cpp:19:11: error: 'cin' was not declared in this scope
     while(cin>>M>>N){
           ^
0_0_25992635_10844.cpp:22:6: error: 'cout' was not declared in this scope
      cout<<ans<<"\n";
      ^