Praise be to Allah.
The basic principle with regard to one who stays in a country is that he should fast with the people of that country and break the fast with them, and it is not permissible to differ from them with regard to the beginning and end of the fast.
But because you were travelling at the time when Ramadan began, there is no blame on you for not fasting, based on the concession that allows the traveller not to fast.
But you have to make up that day that you did not fast, because fasting it was obligatory for you in that country. The fact that you completed thirty days of Ramadan in your country does not mean that the obligation to make it up is waived in your case, because when you fasted the thirtieth day, you did not intend to make up the day when you did not fast.
We put this question to Shaykh ‘Abd ar-Rahmaan al-Barraak (may Allah preserve him) and he ruled that you must make up the fast.
See also the answer to question no. 93432
And Allah knows best.