题意：

思路：

#include <cstdio>
#include <algorithm>
using namespace std;
const int N = 5e3 + 10;
int n,f[N][N],mx[N][N];
int main(){
    scanf("%d",&n);
    for(int i = 1;i <= n;i++){
        scanf("%d",&f[i][i]);
        mx[i][i] = f[i][i];
    }    
    for(int len = 2;len <= n;len++){
        for(int i = 1,j;i + len - 1 <= n;i++){
            j = i + len - 1;
            mx[i][j] = f[i][j] = f[i][j - 1] ^ f[i + 1][j];
            mx[i][j] = max(mx[i][j],max(mx[i][j - 1],mx[i + 1][j]));
        }
    }
    int q;scanf("%d",&q);
    while(q--){
        int l,r;scanf("%d%d",&l,&r);
        printf("%d\n",mx[l][r]);
    }
    return 0;
}