上代码```c
#include <bits/stdc++.h>
#define max 1000010
using namespace std;
int n,a,b,q,arr[max],cnt = 1,age = 1,ans;
int main()
{
cin >> n;
for (int i = 0; i < n; i++)
{
cin >> a >> b;
arr[q++] = a;
if(b != 0)
{
arr[q++] = a^b;
}
}
sort(arr,arr + q);
ans = arr[0];
for (int i = 1; i < q; i++)
{
if (arr[i] == arr[i - 1])
{
cnt++;
}
else
{
if (age < cnt)
{
age = cnt;
ans = arr[i - 1];
}
cnt = 1;
}
}
if (age < cnt)
{
ans = arr[q - 1];
}
cout << ans;
return 0;
}
