src.c: In function 'gbs':
src.c:16:15: error: 'a' undeclared (first use in this function)
for (int i = a; ; i )
^
src.c:16:15: note: each undeclared identifier is reported only once for each function it appears in
src.c:17:21: error: 'b' undeclared (first use in this function)
if (i%a == 0