for(r=0;r<nr;r++)
    {
        IloExpr ex20(env);
        ex20 = H[r];
        for(q=0;q<dm;q++)
        {
            for(p=0;p<dm;p++)
            {
                if (q>p)
                {
                    ex20 -= pow(q-p-1,2)*Z[r][q][p];
                }
            }
        }
        IloRange rng = (ex20 == 0);
        stringstream buffer;
        buffer<<" Contrainte_numero_20_ "<<r<<"_"<<endl;
        rng.setName(buffer.str().c_str());
        mdl1.add(rng);
        ex20.end();
    }