This is my program, it represents the Russian “peasant” way of multiplication, at the moment it works a little differently than I want. Please tell me how I can fix it? There are mandatory input data, as well as mandatory output data.

int rusMult(int a, int b)
{

if (b <= 0)
{
    return rusMult(a, -b);
}

if (b == 0)
{
    return 0;
}
else 
{
    if (b % 2 == 0)
    {
        rusMult(a * 2, b / 2);
    }
    else
    {
        rusMult(a * 2, b / 2) + a;
    }
}


if (b > 0) 
{
    printf("%dt %dtn", a, b);
    int res = rusMult(a * 2, b / 2);
    int ost = b % 2;
    printf("%dt %dt %dt %dtn", a, b, ost, res);
    if (ost == 1)
    {
        res += a;
    }
    
    rusMult(a * 2, b / 2);
}

}