/in/foo.c: In function 'main':
/in/foo.c:8:8: error: 'N' undeclared (first use in this function)
  int a[N],i;
        ^
/in/foo.c:8:8: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:9:8: warning: left-hand operand of comma expression has no effect [-Wunused-value]
  a[1]=1,a[2]=1;
        ^
/in/foo.c:8:6: warning: unused variable 'a' [-Wunused-variable]
  int a[N],i;
      ^