Arnaldo and Bernaldo train for a marathon along a circular track, which has in its center a mast with a flag raised. Arnaldo runs faster than Bernaldo, so that every 30 minutes of running, while Arnaldo gives 15 laps on the track, Bernaldo can only give 10 complete laps. Arnaldo and Bernaldo left at the same moment of the line and ran with constant velocities, both in the same direction. Between minute 1 and minute 61 of the race, how many times did Arnaldo, Bernaldo and the mast become collinear? combinatoricscombinatorial geometrycollineargeometryincenter