#include<stdio.h>
#include<string.h>
#include<ctype.h>

int main(){
    char s[100];
    fgets(s,sizeof(s),stdlin);
    size_t len=strlen(s);
    if(s[len-1]=='\n'){
        s[len-1]='\0';
        len--;
    }
    for(int i=0;i<len;i++){
        if(!(isalpha(s[i]) ||  isspace(s[i]))){
            printf("Invalid Input\n");
            return 0;
        }
    }
    int lastLen =0;
    int i=len-1;
    while(i>=0 && s[i] ==''){
        i--;
    }
    while(i>=0 && isalpha(s[i])){
        lastLen++;
        i--;
    }
    printf("%d\n",lastLen);
    
    return 0;
}