include <stdio.h>

int main()
{

char buff[1024]={0};
char table[128]={0};
int total=0;
gets(buff);

for(int i=0;i<strlen(buff); i++)
{
    table[buff[i]]++;
    if(table[buff[i]] == 1)//如果第一次出现则总数加一
        total++;    
}

printf("%d\n",total);

return 0;

}