#include<stdio.h>
#include<string.h>
#include<ctype.h>
void solve(){
    char s[21];
    if(fgets(s,sizeof(s),stdin)==NULL){
        return;
    }
    int len=strlen(s);
    if(len>0&&s[len-1]=='\n'){
        s[len-1]='\0';
        len--;
    }
    if(len==0){
        return;
    }
    for(int i=0;i<len;i++){
        if(!isalpha(s[i])&&s[i]!=' '){
            printf("Invalid input\n");
            return;
        }
        
    }
    int end==len-1;
    while(end>=0&&s[end]==' '){
        end--;
    }
    if(end<0){
        printf("0\n");
        return;
    }
    int star=end;
    while(start>=0&&s[start]!=' '){
        start--;
    }
    printf("%d\n",end-start);
        
    }
    int main(){
        solve()
        return 0;
    }