The The postal service of Transendive charges the following rates for sending letters and packets:
| type | weight | cost |
| light | 0 to 25 grams | 4 coins |
| medium | 26 to 100 grams | 7 coins |
| heavy | 101 to 250 grams | 10 coins |
The weight is important because the postal items are transported by donkeys, which can carry a limited amount of weight. The direction of the postal service therefore wants to know the average amount of coins paid per kilogram of postal items.
The input file contains the weights (in grams) of various postal items from a recent shipment. Write a program that calculates the average amount of coins paid per kilogram of postal items.