>>700
#include <stdio.h>
int main(void){
char s[100];
int a[256];
fgets(s, 100, stdin);
for (int i = 0; s[i]; ++i)++a[s[i] + 0];
for (int i = 0; s[i]; ++i) {
if (a[s[i] + 0] < 2)printf("%c", s[i]);
a[s[i] + 0] = 0;
}
return 0;
}