#include <stdio.h>
#include <string.h>
#include <ctype.h>
int main(){
    char s[101];
    int count[256] ={0};
    fgets(s,sizeof(s),stdin);
    s[strcspn(s,"\n")] ='\0';
    for(int i=0;s[i != '\0';i++]){
        if(!(isalnum(s[i]) || s[i] == ' ')){
            printf("Inavlid input");
            return 0;
        }
        if(s[i] != ' '){
            count[(unsigned char)s[i]]++;
        }
    }
    for(int i=0;s[i] != '\0';i++){
        if(s[i] != ' ' && count[(unsigned char)s[i]] ==1){
            printf("{%c",s[i]);
        }
    }
    return 0;
    
}