Bridges

Bridges (Hashikake, Hashiwokakero) is a Japanese logic puzzle. You have to connect two numbered circles with one or two lines.

Rules: Draw single and double lines between the numbered circles. Exactly as many lines must end in a numbered circle as the number in the circle indicates.
The lines must be horizontal or vertical, must not bend, and must not cross each other. No lines pass through numbered circles. All number circles are connected by lines, i.e., you can go from any number circle to any other number circle by following the lines.