/in/foo.c: In function 'main':
/in/foo.c:4:21: error: 'n' undeclared (first use in this function)
    4 |         scanf("%d",&n);
      |                     ^
/in/foo.c:4:21: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:9:27: error: 'i' undeclared (first use in this function)
    9 |                 for(j=1;j<i;j++)
      |                           ^