Search in your AppStore or in the Adroid app store for this very usefull app skyscanner. It can be used to find Information for the flights to destinations all over the world. It shows all flights sorted by Price from some Airport to some Airport. I already saved 100 Euro using it. I flew to Burgas anstatt to Varna for 180 euro. If I choose the way from Frankfurt to Varna it is shown with 1 stop in Sofia and costs over 250 euro.