int side, lim, symbs;

    do {
        cout << "Enter the side: "; cin >> side;
    } while(side<2);

    symbs=1;
    lim = 1;

    while(side>=1)
    {
        --side;
        while(symbs<=lim)
        {
            cout << "*";
            ++symbs;
        }
        symbs=1;
        ++lim;
        cout << endl;
    }