files = ['./input-7-1.txt', './input-7-2.txt']

for f in files:
  with open(f,'r') as fi:
    lowest_rate = {}

    lines = fi.readlines()
    for l in lines:
      if (l != '-1'):
        [origin_port, destination_port, shipping_rate, carrier_name] = l.strip().split(' ')
        shipping_rate = float(shipping_rate)

        if (destination_port in lowest_rate.keys()):
          if shipping_rate < lowest_rate[destination_port]['shipping_rate'] :
            lowest_rate[destination_port] = {'origin_port': origin_port, 'destination_port': destination_port, 'shipping_rate': shipping_rate, 'carrier_name': carrier_name}
        else:
          lowest_rate[destination_port] = {'origin_port': origin_port, 'destination_port': destination_port, 'shipping_rate': shipping_rate, 'carrier_name': carrier_name}

  print(f)
  for v in lowest_rate.values():
    print(f"The lowest shipping rate from {v['origin_port']}' to {v['destination_port']} is {v['shipping_rate']}.")
  print()