In the following drawing, eight wires cut the screen perpendicularly at the indicated points 1 to 8. A wire labelled with the integer k bears the current kI. For those with odd k, the current flows out of the screen; for those with even k it flows into it. Evaluate f, B · dr, where C is the closed path shown in red, in the direction indicated by the arrowhead. This integral is how many times lI? (It's an integer)

In the following drawing, eight wires cut the screen perpendicularly at the indicated points 1 to 8. A wire labelled with the integer k bears the current kI. For those with odd k, the current flows out of the screen; for those with even k it flows into it. Evaluate f, B · dr, where C is the closed path shown in red, in the direction indicated by the arrowhead. This integral is how many times lI? (It's an integer)