char s[],a[1030][11];r,t,i,n;c(a,b){r=strcmp(a,b);}main(l){for(n=strlen(gets(s));i--?a[t][i]=s[t&1<<i?++l:--r]:(i=r=n,l=-1,t++<1<<n););for(qsort(a,t,11,c);t;l+=!!strcmp(a[t],a[t--]));r=!printf("%d",l);}