1084 Broken Keyboard

#include<iostream>

#include<cctype>

#include<string>

using namespace std;

int main(){

string s1,s2,ans;

cin>>s1>>s2;

for(int i=0;i<s1.length();i++){

if(s2.find(s1[i])==string::npos&&ans.find(toupper(s1[i]))==string::npos){

ans+=toupper(s1[i]);

}

}

cout<<ans<<endl;

return 0;

}