All you have to do is to give your best out of your work and just ignore those salaries of your co-workers for now. Earn more experiences and qualifications and bigger rate will follow. In the first place , you accepted that offer.
Just a sincere thought and I am not for argument. Salaries must be determined by experience, qualification and quality of work regardless of who and what type of person you are. It is unfair for those underrated nationalities who are able to work better, more experienced and more qualified for a specific position but is given a lower rate than a less experienced, a mediocre and average qualified person but a member of a high paid nationality. Remember that we are living and spending money in the same place. Have a good day to everyone!!!