1 #include <stdio.h> 2 #include <algorithm> 3 using namespace std; 4 #define maxn 1000 5 int a[maxn],n; 6  7 int main() 8 {     9     while(scanf("%d",&n), n)10     {11         int one = 0, two = 0, three = 0;12         for(int i=0; i<n; i++)13         {14             scanf("%d",&a[i]);15             three = two & a[i];16             two = two | one & a[i];17             one = one | a[i];18             two = two & ~three;19             one = one & ~three;20         }      21         printf("%d\n",one);22     }23     return 0;24 }