/in/ex2.c: In function 'ex3':
/in/ex2.c:4:8: error: 'n' undeclared (first use in this function)
     if(n%c==0 && b%c==0){
        ^
/in/ex2.c:4:8: note: each undeclared identifier is reported only once for each function it appears in
/in/ex2.c: In function 'main':
/in/ex2.c:13:20: error: 'a' undeclared (first use in this function)
     scanf("%d %d",&a,&b);
                    ^
/in/ex2.c:13:23: error: 'b' undeclared (first use in this function)
     scanf("%d %d",&a,&b);
                       ^