Select the right option from the given alternatives
I walked 20 m towards east from a point S and then turned right and walked another 20 m. Now I turned to my left and walked 10 m and turning to my right I walked another 10 m. Finally I turned to my right and walked 30 m to reach a point F. What is the shortest straight distance between points S and F?
20 m
25 m
30 m
40 m
50 m