int hash(square x,int yk){
    int sum;
    int res=1;
    for (int i=0;i<N;i++){
        sum=0;
        for (int j=0;j<N;j++){
            if (x.box[i][j]!='0'){
                sum+=(j+1)*(x.box[i][j]-'0');
            }
        }
        sum*=i+1;
        res*=sum;
    }
    res+=yk;
    return res;
}