little penguin Polo adore string but adore string length nOne day want find string meet follow condition the string consist n lowercase english letter string length equal n exactly k letter distinct no neighbouring letter string coincide represent string ss1s2 sn follow inequality hold sisi11 in among string meet point 1 2 require string lexicographically small help find string state string do not existstre xx1x2 xp lexicographically string yy1y2 yq pq x1y1x2y2 xpyp number r rprq x1y1x2y2 xryr xr1yr1 the character string compare ascii code