Some particle starts moving from rest with constant acceleration. After time $t$ from the start of the motion, the particle's velocity became $v$. What distance will the particle travel in time $2t$? \InputFile Each line is a separate test and contains two integers --- the particle's velocity $v~(0 \le v \le 100)$ and the time $t~(0 \le t \le 200)$, at which the particle reached this velocity. \OutputFile For each test, print the distance the particle will move in time $2t$ on a separate line.