foo.c: In function ‘main’:
foo.c:16:23: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘<=’ token
   16 |         for(int i=k1,i<=k2;i++)
      |                       ^~
foo.c:16:31: error: expected ‘;’ before ‘)’ token
   16 |         for(int i=k1,i<=k2;i++)
      |                               ^
      |                               ;