$0=tolower($0){for(gsub(/[^a-z ]/,n=_);$++n;v[i+1]=$n)for(i=++m;--i&&$n>v[i];)v[i+1]=v[i]}END{for(;++c*m;w=v[m])if(w&&w!=v[--m]){print--c,w
c=1}}