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

int main() {
char s[25];
int valid = 1;

fgets(s, sizeof(s), stdin);
size_t len = strlen(s);
if (len && s[len-1] == '\n') s[len-1] ='\0';

for (int i =0; s[i] ; i++) {
    if ( ! isalpha (s[i]) && !isspace (s[i])) {
        valid = 0 ;
        break;
    }
} 
    if (! valid) {
        printf("Invalid input");
        return 0;
    }
        char*last = NULL;
        char*token = strtok(s, " ");
        while (token); {
            last=token;
            token = strtok(NULL, " ");
    }
if (last) {
printf("%d", (int) strlen (last));
}else {
printf("0");
    }
return 0;
}