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

int main() {
    char str[101];
    
    fgets(str, sizeof(str), stdin);
    
    str[strcspn(str, "\n")] = '\0';
    
    int length = strlen(str);
    int isNumber = 1;
    
    for(int i = 0;i<length;i++) {
        if(!iddigit(str[i])) {
            isNumber = 0;
            
            break;
        }
    }
    if(isNumber)
       printf("Invalid input");
    else
       printf("%d", length);
    return 0;
}