1.100: Customer 0 arrives
1.100: Customer 0 service begin (by Counter 0)
2.200: Customer 1 arrives
2.200: Customer 1 departed
3.100: Customer 0 service done (by Counter 0)
3.100: Customer 0 departed
3.300: Customer 2 arrives
3.300: Customer 2 service begin (by Counter 0)
5.300: Customer 2 service done (by Counter 0)
5.300: Customer 2 departed
