foo.c: In function ‘main’:
foo.c:16:20: error: expected ‘;’ before ‘)’ token
   16 |         for(j=1,j++)
      |                    ^
      |                    ;
foo.c:16:20: error: expected expression before ‘)’ token
foo.c:21:9: error: ‘n’ undeclared (first use in this function)
   21 |         n=min
      |         ^
foo.c:21:9: note: each undeclared identifier is reported only once for each function it appears in
foo.c:21:14: error: expected ‘;’ before ‘m’
   21 |         n=min
      |              ^
      |              ;
   22 |         m=c*j+d*(min/b);
      |         ~     
foo.c:23:26: error: ‘m’ undeclared (first use in this function)
   23 |         for(i=1;i<=n&&i<=m;i++)
      |                          ^
foo.c:26:25: error: ‘max’ undeclared (first use in this function)
   26 |                         max=i;
      |                         ^~~