Depends with the nationality. Countries that can avail visa upon arrival are:
Andora, Germany, Monaco, Switzerland,
Austria, Greece, Netherlands, USA,
Australia, Hong Kong, New Zealand, Vatican,
Belgium, Ice Land, Norway,
Brunei, Ireland, Portugal,
Canada, Italy, San Marino,
Denmark, Japan, Singapore,
England, Liechenstein, South Korea,
Finland, Luxemberg, Spain,
France, Malaysia, Sweden