int main(void) {
char s[1000] = "";
while(gets(s)) {
int result[131] = {0};
char s1[1000] = "";
int maxIndex = 0;
int max = 0;
int i = 0;
int count = 0;
int j =0 ;
for(i = 0; i < strlen(s); i++) {
result[s[i]]++;
}
for(i = 0; i < 131; i++) {
if(result[i] > 0)
count++;
}
while(j < count) {
max = 0;
maxIndex = 0;
for(i = 0; i < 131; i++) {
if(max < result[i]) {
max = result[i];
maxIndex = i;
}
}
result[maxIndex] = 0;
s1[j] = (char)maxIndex;
j++;
}
printf("%s\n", s1);
}
}