Question 70
Three grasshoppers are at $(0,0)$, $(0,1)$ and $(1,0)$ on a sheet of squared paper. Every minute one grasshopper jumps to another grid point so that its jump is parallel to the line through the other two grasshoppers. Is it possible that, after some time, the grasshoppers are at $(-1,0)$, $(1,0)$ and $(0,1)$?