int PosFirstMinDig(int a)
{
    if (a<=0)return -1;
    int mnc=9,nmc=-1,k=0;
    do
    {
        int c=a%10;
        k++;
        if (c<=mnc)
        {
            mnc=c;nmc=k;
        }
        a=a/10;
    }while(a!=0);
    return k+1-nmc;
}