#include<stdio.h>
#include<string.h>
#include<ctype.h>
int main(){
    char s[100];
    fgets(s,sizeof(s),stdin);
    s[strcspn(s,"\n")]='\0';
    int n=strlen(s);
    for(int i=0;i<n;i++){
        if(!isalpha(s[i])&&!isspace(s[i])){
            printf("Invalid input\n");
            return 0;
        }
    }
    int end=n-1;
    while(end>-0&&isspace(s[end])){
        end--;
    }
    int end = n-1;
    while(end>=0&&isspace(s[end])){
        length++;
        end--;
    }
    printf("%d\n",length);
    return 0;
    }