Closest capital acrostics- O capitals

Name the closest capital starting with the letters of the capital's name. If a letter appears a second time, name the second closest capital. If a letter appears a third time, name the third closest capital, etc. Previous quizzes in the series I call ‘Learn how to type Islamabad really well’: A, B1, B2, C,D,FG,HIJ,,K,L,M,N