#include <stdio.h>
#include <string.h>
#include <ctype.h>
void reverseSentence(char str[],int start,int end){
    if (start>=end )return;
    char temp=str[start];
    str[start]=str[end];
    str[end]=temp;
    reverseSentence(str,start + 1,end -1);
}
int containsdigit (char str[]){
    for (int i=0;str[i]!='\0';i++){
        if (isdigit(str[i]))return 1;
    }
    return 0;
    
}
int main(){
    char sentence[101];
    fgets(sentence,sizeof(sentence),stdin);
    sentence [strcspn(sentence,"\n")]=0;
    if(containsDigit(sentence)){
        printf("invalid input ");
        return 0;
    }
    int len =strien(sentence );
    reverseSentence(sentence,0, len-);
    printf("%s",sentence);
    return 0;
}