1.000: Customer 0 arrives
1.000: Customer 0 service begin (by Counter 0)
1.200: Customer 1 arrives
1.200: Customer 1 service begin (by Counter 1)
1.400: Customer 2 arrives
1.400: Customer 2 departed
1.600: Customer 3 arrives
1.600: Customer 3 departed
2.000: Customer 0 service done (by Counter 0)
2.000: Customer 0 departed
2.100: Customer 4 arrives
2.100: Customer 4 service begin (by Counter 0)
2.200: Customer 1 service done (by Counter 1)
2.200: Customer 1 departed
3.100: Customer 4 service done (by Counter 0)
3.100: Customer 4 departed
