/in/foo.c: In function 'main':
/in/foo.c:8:23: error: expected expression before ';' token
    8 |                 for(j=;j<=i;j++)
      |                       ^
/in/foo.c:4:17: warning: unused variable 'sum' [-Wunused-variable]
    4 |         int i,j,sum;
      |                 ^~~