/in/foo.c:3:1: error: unknown type name 'using'
 using namespace std;
 ^
/in/foo.c:3:17: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'std'
 using namespace std;
                 ^
/in/foo.c: In function 'main':
/in/foo.c:7:8: error: 'Impossible' undeclared (first use in this function)
 printf(Impossible!"")
        ^
/in/foo.c:7:8: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:7:18: error: expected ')' before '!' token
 printf(Impossible!"")
                  ^
/in/foo.c:8:1: error: expected ';' before 'return'
 return 0;
 ^