#include <stdio.h>
#include <algorithm>
using namespace std;

char buffer[100];
char buffer2[100];
int n;

int getpos(char x){
	for (int i=0;i<n;i++)
		if (buffer2[i]==x) return i;
	return -1;
}
int main(){
	while(scanf("%s", buffer)!=EOF){
		strcpy(buffer2, buffer);
		n = strlen(buffer);

		sort(buffer2, buffer2+n);
		int swaps=0;
		for (int i=0;i<n;i++){
			while (buffer[i]!=buffer2[i]){
				swap(buffer[i], buffer[getpos(buffer[i])]);
				swaps++;
			}
		}

		printf("%d\n", swaps);
	}
		
	return 0;
}