Java
package PAT_A1084_Broken_Keyboard;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String a = sc.next();
String b = sc.next();
boolean[] st = new boolean[210];
b += '#';
int j = 0;
for (int i = 0; i < a.length(); i++) {
char x = Character.toUpperCase(a.charAt(i));
char y = Character.toUpperCase(b.charAt(j));
if (x == y) {
j++;
} else if (!st[x]) {
System.out.print(x);
st[x] = true;
}
}
sc.close();
}
}
C++
#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
string a, b;
bool st[210];
int main() {
cin >> a >> b;
b += '#';
for (int i = 0, j = 0; i < a.size(); i++) {
char x = toupper(a[i]), y = toupper(b[j]);
if (x == y) j++;
else if (!st[x]) {
cout << x;
st[x] = true;
}
}
return 0;
}