/in/foo.c: In function 'main':
/in/foo.c:8:13: error: 'i' undeclared (first use in this function)
    8 |         for(i=1;i<+n,i++)
      |             ^
/in/foo.c:8:13: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:8:21: warning: left-hand operand of comma expression has no effect [-Wunused-value]
    8 |         for(i=1;i<+n,i++)
      |                     ^
/in/foo.c:8:25: error: expected ';' before ')' token
    8 |         for(i=1;i<+n,i++)
      |                         ^
      |                         ;