include

using namespace std;

define m 1000005

int a[m];

int main() {

int n;
scanf("%d", &n);
for (int b = 0; b < n; b++) {
	scanf("%d", &a[b]);
}
for (int b = 0; b < n; b++) {
	for (int c = b + 1; c < n; c++) {
		if (a[b] == a[c]) {
			a[b] = -1;
			a[c] = -1;
		}
	}
}
for (int b = 0; b < n; b++) {
	if (a[b] != -1) {
		printf("%d", a[b]);
	}
}
return 0;

}