Which season is your favourite season, spring, summer, autumn or winter? I like autumn best. Autumn is the time for harvest(收获). In autumn I can eat many different fruits：apples, pears, grapes and so on. I can also eat fresh vegetables. Autumn is cool. I feel comfortable(舒适的). I am happy to see the leaves turn red and yellow.

已知a>0,b>0，若直线l:ax+by=1平分圆x²+y²-2x-2y-3=0的周长，则$\frac{1}{a}+\frac{2}{b}$的最小值为(   ）