#include <bits/stdc++.h>
using namespace std;

int a[100010];
int solve(int L, int R, int shift, int acc){
	if(shift < 0){
		return acc;
	}

	int p = L;
	for(int i=L;i<R;i++){
		if((a[i] >> shift) & 1){
			swap(a[p], a[i]);
			++p;
 		}
	}

	if(p == L || p == R){
		return solve(L, R, shift - 1, acc << 1);
	}

	return min(
		solve(L, p, shift - 1, (acc << 1) | 1),
		solve(p, R, shift - 1, (acc << 1) | 1)
	);
}

int main(){
	int N;
	cin >> N;
	for(int i=0;i<N;i++)cin >> a[i];
	
	cout << solve(0, N, 31, 0) << endl;
	return 0;
}