In the middle of the above sequence, on the third and fourth string, the guitarist must finger the same fret for both strings. There are more fingerings than humans have fingers, though both of these problems are solved by first fretting the initial string (fourth on the downstroke) with the tip of the ring finger, then rolling into the next string by fretting it with the pad of the same finger. In the upstroke, one frets the third string first, reversing the rolling action. Also note that on the lowest and highest strings in the shape, two notes must be played immediately following each other, but on the same string. This is where legato comes into effect, so that the guitarist can sustain a fluid picking motion.