#include<stdio.h>
#include<string.h>
#include<ctype.h>
int main(){
    char s[101];
    int i,len,lastlen=0;
    int valid=1;
    fgets(s, sizeof(s), stdin);
    s[strcspn(s, "\n")]='\0';
    len=strlen(s);
    for(i=0;i<len;i++){
        if(!isalpha(s[i])&&s[i]!isspace(s[i])){
            valid=0;
            break;
        }
}
if(!valid)
{
    printf("Invalid input\n");
    return 0;
}
i=len-1;
while(i>=0&&s[i]==' ')
{
    i--;
}
while(i>=0&&isalpha(s[i]))
{
    lastlen++;
    i--;
}
printf("%d\n",lastlen);
return 0;
}