XOR-pyramid

#include <bits/stdc++.h>
using namespace std;
const int maxn=5009;
int a[maxn],n,dp[maxn][maxn],f[maxn][maxn];
int main()
{
    cin >> n;
    for(int i=1;i<=n;i++)    cin >> a[i],dp[i][i]=a[i],f[i][i]=a[i];
    for(int i=1;i<n;i++)
    {
        dp[i][i+1]=a[i]^a[i+1];
        f[i][i+1]=max( f[i][i],f[i+1][i+1] );
        f[i][i+1]=max( f[i][i+1],dp[i][i+1] );
    }
    for(int l=3;l<=n;l++)
    for(int i=1;i+l-1<=n;i++)
    {
        int j=i+l-1;
        dp[i][j] = (dp[i][j-1]^dp[i+1][j] );
        f[i][j]=max(f[i][j-1],f[i+1][j] );
        f[i][j]=max( f[i][j],dp[i][j] );
    }
    int q;
    cin >> q;
    while( q-- )
    {
        int l,r;
        cin >>l >> r;
        cout << f[l][r] << '\n';
    }
}