#include <stdio.h>

int main() 
{
    char arr[500];
    scanf("%s",arr);
    int count = 0;
    char cmp[128] = {0};
    int ret =0;
    while(arr[count++] != '\0')
    {
        ;
    }
    for(int i = 0;i < count - 1;i++)
    {
        cmp[arr[i]]++;
    }
    for(int i = 0;i < 128;i++)
    {
        if(cmp[i] > 0)
        {
            if(i>=0 && i <= 127)
            {
                ret++;
            }
        }
        cmp[i] = '\0';
    }
    printf("%d\n",ret);

    return 0;
}