Диафантово уравнение

#include <cstdio>
#include <algorithm>
typedef long long ll

template<typename T>
T gcd_ext(const T a, const T b, T& x, T& y)
{
    if (b == 0)
    {
        x = 1;
        y = 0;
        return a;
    }

    const T d = gcd_ext(b, a % b, x, y);
    x -= (a / b) * y;
    std::swap(x, y);
    return d;
}

int main()
{
    ll a = 0, b = 0, x = 0, y = 0, c = 0;
    std::scanf("%lld%lld%lld", &a, &b, &c);

    const ll d = gcd_ext(a, b, &x, &y);

    if (c % d != 0)
        std::puts("-1");

    else
    {
        ll t = 0;
        const ll Y = y;
        const ll X = x;

        x = (c / d) * X;
        y = (c / d) * Y;

        if (x == 0)
            goto END;

        else if (x > 0)
        {
            while (x > 0)
            {
                t--;
                x = (c / d) * X + t * (b / d);
                y = (c / d) * Y - t * (a / d);
            }

            if (x == 0)
                goto END;

            t++; //доходим до сюда, когда x < 0
            x = (c / d) * X + t * (b / d);
            y = (c / d) * Y - t * (a / d);
        }

        else
        {
            while (x < 0)
            {
                t++;
                x = (c / d) * X + t * (b / d);
                y = (c / d) * Y - t * (a / d);
            }
        }

    END: std::printf("%lld %lld", x, y);
    }

    return 0;
}