you give string s integer k you choose k letter s append end stringreturn lexicographically small string apply mention step number move Example 1input s cba k 1Output acbexplanation in 1st character c end obtain string bacin second 1st character b end obtain final result acbexample 2Input s baaca k 3output aaabcexplanation in 1st character b end obtain string aacabin second 3rd character c end obtain final result aaabc Constraints1 k slength 1000 consist lowercase english letter