Romania has borders with Bulgaria, Hungary, Ukraine, Serbia and Moldova; also the Black Sea is a border.
Vietnam
No borders between Romania and Greece. Romania has borders with Serbia, Hungary, Ukraine, Moldova, Bulgaria. Greece has borders with Albania, Macedonia, Bulgaria, Turkey. ___ Bulgaria borders Greece and Romania.
Republic of Croatia, Borders Hungary and Bosnia, across the Adriatic Sea from Italy.
Ukraine
Russia, Moldova, Romania, Poland, Slovakia, Belarus, Hungary, The Black Sea and The Sea of Azov.
Romanian borders are with: Moldova, Ukraine, Hungary, Serbia, Bulgaria and the Black Sea.
Austria borders both Hungary and Switzerland.
Hungary, Serbia, Bulgaria, Moldova, Ukraine and the Black Sea.
No nation's capital city borders Hungary. Bratislava, the capital of Slovakia, comes fairly close to Hungary, but actually borders Austria. Vienna, the capital of Austria, is also considerably close to Hungary.
Hungary, Serbia, Bulgaria, Moldova, Ukraine (and the Black Sea).
Not four, but five countries ! Bulgaria Moldavia Ukraine Hungary Serbia Black Sea