/in/foo.c: In function 'main':
/in/foo.c:14:9: error: unknown type name 'bool'
         bool isPrime = true;  
         ^~~~
/in/foo.c:14:24: error: 'true' undeclared (first use in this function)
         bool isPrime = true;  
                        ^~~~
/in/foo.c:14:24: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:18:27: error: 'false' undeclared (first use in this function)
                 isPrime = false;  
                           ^~~~~