#include <stdio.h>
#include <string.h>
#include <ctype.h>
int main() {
    char str[101];
    int isDigitonly=1;
    fgets(str,sizeof(str), stdin);
    str[strcspn(str,"\n")]='\0';
    for(int i=0; str[i]!='\0';
    if(!isdigit((unsigned char)str[i])){
        isDigitonly=0;
        break;
        
    }
}
if(isDigitonly){
    printf("Invalid input");
    
}else{
    printf("%lu",strlen(srt));
}
return 0;
}