include "std/io.zr"

func main[] : i64
    out := 0

    for a in 500..1000
        for b in 500..1000
            if a * b > out
                s := (a * b)->to_str()
                s_rev := s->reverse()
                if s->equal(s_rev)
                    out = a * b
                s->free()
                s_rev->free()
    io.println_i64(out)