def find_minimum_distance(a,b,s)
	r_arr1=s.scan(/#{a}[^#{a}#{b}]*#{b}/)
	r_arr2=s.scan(/#{b}[^#{a}#{b}]*#{a}/)
	r_arr=r_arr1+r_arr2
	r_arr.min_by{|a| a.length}.length-2
end

p find_minimum_distance("a", "b", "bsssasssbsa")
p find_minimum_distance("a", "b", "asssbsssasb")
p find_minimum_distance("a", "b", "assssb")