#pragma GCC optimize("O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma comment(linker, "/stack:200000000")
#include<ios>
char buf[1<<17],*p1=buf,*p2=buf;
inline int getc(){
return p1==p2&&(p2=(p1=buf)+fread_unlocked(buf,1,1<<17,stdin),p1==p2)?EOF:*p1++;
}
inline void write(int x) {
static int stk[9],top=0;
int *ptr;
ptr = &stk[0];
while(x){*ptr=x%10;x/=10;ptr++;}
ptr--;
while(ptr>=(&stk[0])){putchar_unlocked(*ptr+'0');ptr--;}
}
inline int read() {
int ret=0;
char ch=getc();
while(ch>='0'&&ch<='9')
ret=(ret<<1)+(ret<<3)+ch-'0',ch=getc();
return ret;
}
int main(){
    int 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);
    }
    write(q);
}