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#include<iostream>
#include<cmath>
#include<string>
#include<cstdio>
#include<algorithm>
using namespace std;
int n,b[130];
string a;
int main(){
//freopen("1167.in","r",stdin);
//freopen("1167.out","w",stdout);
cin>>a;
for(int i=0;i<=a.size()-1;i++) b[a[i]]++;
for(int i=0;i<=a.size()-1;i++){
if(b[a[i]]!=0) cout<<a[i];
b[a[i]]=0;
}
//fclose(stdin);
//flose(stdout);
return 0;
}
90分;哪错了,???????
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