小结论：我们只要把所有的都异或起来就是最小的
$a \oplus b\lt a+b$

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;
template<class T>
void read(T &now){
    now=0;
    char c=getchar();
    int f=1;
    while((!isdigit(c))){
        if(c=='-') f=-1;
    //  cout<<isdigit(c)<<" "<<c<<" ";
        c=getchar();
    }
    while(isdigit(c)){
        now=(now<<1)+(now<<3)+c-'0';
        c=getchar();
    }
    now*=f;
}
int n;
int a[1000001];
int ans;
int main(){
    read(n);
    for(int i=1;i<=n;++i){
        read(a[i]);
        ans^=a[i];
    }
    cout<<ans;
    return 0;
}