Levko love string length n consist lowercase english letter he string s for stre t length n Levko define beauty relative s number pair index j 1ijn substring tij lexicographically large substring sijthe boy wonder string t beauty relative s equal exactly k Help find remainder division number 1000000007 1097A substre sij string ss1s2 sn stre sisi1 sjstring xx1x2 xp lexicographically large string yy1y2 yp number r rp x1y1x2y2 xryr xr1yr1 the string character compare ascii code