#include <vector>
#include "secret.h"
#include <assert.h>
#define N 1050
int n, *a;
std::vector<int> pre[N<<1], suf[N<<1];
void build(int v, int l, int r)
{
if (l == r)
{
pre[v] = suf[v] = {a[l]};
return;
}
int m=(l+r)/2, vl=v+1, vr=v+(m-l+1)*2;
suf[v].resize(m-l+1);
suf[v][m-l] = a[m];
for (int i = m-l-1, j = m - 1; j >= l; --j, --i)
suf[v][i] = Secret(a[j], suf[v][i+1]);
pre[v].resize(r-m);
pre[v][0] = a[m+1];
for (int i = 1; i < r-m; ++i)
pre[v][i] = Secret(pre[v][i-1], a[m+1+i]);
build(vl, l, m);
build(vr, m+1, r);
}
int qry(int v, int l, int r, int x, int y)
{
int m = (l+r)/2, vl=v+1, vr=v+(m-l+1)*2;
if (l <= x && y <= m) return qry(vl, l, m, x, y);
if (m + 1 <= x && y <= r) return qry(vr, m+1, r, x, y);
int al = suf[v][suf[v].size()-1-(m-x)], ar = pre[v][y-m-1];
return Secret(al, ar);
}
void Init(int n_, int *a_)
{
n = n_, a = a_;
build(0, 0, n-1);
}
int Query(int l, int r)
{
return qry(0, 0, n-1, l, r);
}
