#include<stdio.h>
void reverse(){
    char ch;
    if(scanf("%c",&ch)!=1)
    return;
    if(ch==''\n')
    return ;
    if(ch>='0'&&ch<=9)
    hasDigit=1;

reverse();
if(!hasDigit)
printf("%c",ch);
}
int main(){
    reverse();
    if(!hasDigit){
        printf("Invalid innput");
    }
    return 0;
}