/in/foo.c: In function 'main':
/in/foo.c:11:17: error: expected expression before 'int'
   11 |                 int j=1;
      |                 ^~~
/in/foo.c:12:16: error: 'j' undeclared (first use in this function)
   12 |         switch(j)
      |                ^
/in/foo.c:12:16: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:15:9: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   15 |         if(n%i==0)
      |         ^~
/in/foo.c:16:41: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   16 |         printf("%d is not a primer!",n);break;
      |                                         ^~~~~