global S='bnfhgfdhghfdhjdjhfhjffh'
function f(i,j) {
 if (i>=j) return 0 ;
 else if (S[i]==S[j]) return f(i+1,j-1) ;
 else return min(f(i+1,j),f(i,j-1))+1 ;
}
print f(1,length(s)) ;