/in/foo.cc:1:1: error: 'include' does not name a type
 include <bits/stdc++.h>
 ^~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:6:5: error: 'cin' was not declared in this scope
     cin >> a >> b;
     ^~~
/in/foo.cc:7:5: error: 'cout' was not declared in this scope
     cout <<"S="<< fixed << setprecision(2) << (a * b) / 2.0 << endl;
     ^~~~
/in/foo.cc:7:19: error: 'fixed' was not declared in this scope
     cout <<"S="<< fixed << setprecision(2) << (a * b) / 2.0 << endl;
                   ^~~~~
/in/foo.cc:7:42: error: 'setprecision' was not declared in this scope
     cout <<"S="<< fixed << setprecision(2) << (a * b) / 2.0 << endl;
                                          ^
/in/foo.cc:7:64: error: 'endl' was not declared in this scope
     cout <<"S="<< fixed << setprecision(2) << (a * b) / 2.0 << endl;
                                                                ^~~~