#include <stdio.h>
#define N 8
int a[10] = {0};
int b[10] = {0};
void func(int n)
{
    if (n == 0)
    {
        int aa, bb;
        aa = 0;
        for (int i = 0; i < N / 2; ++i)aa = aa * 10 + b[i];
        if (aa<1234)
        {
            return;
        }
        bb = 0;
        for (int i = N / 2; i < N; ++i)bb = bb * 10 + b[i];
        if (aa > bb)return;
        int ab = aa * bb;
        while (ab)
        {
            int w = ab % 10;
            for (int i = 0; i < N; ++i)
                if (b[i] == w)return;
            ab /= 10;
        }
        printf("answer : %d %d = %d\n", aa, bb, aa * bb);
        return;
    }
    for (int i = 0; i < 10; ++i)
    {
        if (a[i] == 0)
        {
            a[i] = 1;
            b[n - 1] = i;
            func(n - 1);
            a[i] = 0;
        }
    }
}
int main()
{
    func(N);
    return 0;
}