#pragma GCC optimize("O3,unroll-loops,no-stack-protector,fast-math")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include<cstdio>
#include<stdint.h>
char buf[1<<16],*p1=buf,*p2=buf;
inline int getc(){
return p1==p2&&(p2=(p1=buf)+fread_unlocked(buf,1,1<<16,stdin),p1==p2)?EOF:*p1++;
}
inline int read() {
uint_fast64_t ret=0;
char ch(getc());
while(ch>='0'&&ch<='9')ret=(ret<<1)+(ret<<3)+ch-'0',ch=getc();
return ret;
}
int main(){
    uint_fast64_t n,p(0),q(0),b;
    n=read();
    for(int i(0);i<n;++i){
        b=read();
        p=q&(p^b);
                q=p|(q^b);
    }
    printf("%d",q);
}