#include<stdio.h>
int hasdigit=0;
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 input");
    }
    return 0;
}