Sona is in-charge of inviting the guest. She don't know how much far they are from her place. She knows the guest house co-ordinates (gx,gy)and the co-ordinates of the place where she is standing(sx,sy). Help her to calculate the distance between the guest house and her place.

Input

First line contains guest house co-odinates gx,gy and the second line contains Sona's coordinates sx,sy

Output

Print the distance and round off it to 5 digits

constraints

1< = gx,gy,sx,sy< = 10

SAMPLE INPUT
2 5
2 6

SAMPLE OUTPUT
1.00000

Explanation

Sona is in-charge of inviting the guest. She don't know how much far they are from her place. She knows the guest house co-ordinates and the co-ordinates of the place where she is standing. Help her to calculate the distance between the guest house and her place.

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