#include<stdio.h>
#include<ctype.h>
#include<string.h>
int main(){
char s[105];
fgets(s,sizeof(s),stdin);
int n=strlen(s);
if(s[n - 1] == '\n'){
    s[n - 1]='\0';
    n--;
}
int seen[256]={0};
char result[105];
int k=0;
for(int i = 0;i<n;i++){
    char c=s[i];
    if(!(isalnum(c)||c==' ')){
        printf("Invalid input");
        return 0;
    }
    if(!seen[(unsigned char)c]){
        result[k++]=c;
        seen[(unsigned char)c]=1;
    }
}
result[k]='\0';
printf("%s, result");
return 0;
}