/in/foo.c: In function 'main':
/in/foo.c:7:2: error: 'c' undeclared (first use in this function)
  c=a+b;
  ^
/in/foo.c:7:2: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:9:1: error: expected ';' before '}' token
 }
 ^