Flying Right  (flyright.X)

Figuring that they cannot do worse than the humans have, Farmer Ran's cows
have decided to start an airline. Being cows, they decide to cater to the
heretofore-untapped market of cows as passengers. They plan to serve the
cows who live along the western coast of Lake Michigan. Each morning, they
will fly from the northern-most point of the coast southward towards
Chicowgo, making many stops along the way. Each evening, they will fly back
north to the northern-most point.

They need your help to decide which passengers to carry each day. Each of N
(1 <= N <= 10,000) farms numbered 1..N along the coast contains an airport
(Farm 1 is northern-most; farm N is southern-most). On this day, K (1 <= K
<= 50,000) groups of cows wish to travel. Each group of cows wants to fly
from a particular farm to another particular farm.  The airline, if it
wishes, is allowed to stop and pick up only part of a group. Cows that
start a flight, however, must stay on the plane until they reach their
destination.

Given the capacity C (1 <= C <= 100) of the airplane and the groups of cows
that want to travel, determine the maximum number of cows that the airline
can fly to their destination.

PROBLEM NAME:  flyright

INPUT FORMAT:

* Line 1: Three space-separated integers: K, N, and C.

* Lines 2..K+1: Each line contains three space-separated integers S,
        E, and M that specify a group of cows that wishes to travel. 
        The M (1 <= M <= C) cows are currently at farm S and want to
        travel to farm E (S and E will be distinct).

SAMPLE INPUT:

4 8 3
1 3 2
2 8 3
4 7 1
8 3 2

INPUT DETAILS:

Four groups of cows, eight farms, and three seats on the plane.

OUTPUT FORMAT:

* Line 1: The maximum number of cows that can be flown to their
        destination. This is the sum of the number of cows flown to
        their destination on the flight southward in the morning plus
        the number of cows flown to their destination on the flight
        northward in the evening.

SAMPLE OUTPUT:

6

OUTPUT DETAILS:

In the morning, the flight takes 2 cows from 1->3, 1 cow from 2->8, and 1
cow from 4->7.  In the evening, the flight takes 2 cows from 8->3.