Score : 300 points
In a public bath, there is a shower which emits water for T seconds when the switch is pushed.
If the switch is pushed when the shower is already emitting water, from that moment it will be emitting water for T seconds. Note that it does not mean that the shower emits water for T additional seconds.
N people will push the switch while passing by the shower. The i-th person will push the switch t_i seconds after the first person pushes it.
How long will the shower emit water in total?
Input is given from Standard Input in the following format:
N T t_1 t_2 ... t_N
Assume that the shower will emit water for a total of X seconds. Print X.
2 4 0 3
7
Three seconds after the first person pushes the water, the switch is pushed again and the shower emits water for four more seconds, for a total of seven seconds.
2 4 0 5
8
One second after the shower stops emission of water triggered by the first person, the switch is pushed again.
4 1000000000 0 1000 1000000 1000000000
2000000000
1 1 0
1
9 10 0 3 5 7 100 110 200 300 311
67