#include <bits/stdc++.h>

#define int long long
#define pll pair<int, int>
#define rep(i, s, e, st) for (int i = s, __##i = e; i <= __##i; i += st)
#define per(i, s, e, st) for (int i = s, __##i = e; i <= __##i; i -= st)
#define lowbit(x) ((x) & (-(x)))
#define lc(x) ((x) << 1)
#define rc(x) (((x) << 1) | 1)
#define clr(dst, size) memset(dst, 0, (sizeof(int)) * size)
#define initval(dst, val, size) memset(dst, val, (sizeof(int)) * size)
#define cpy(from, to, size) memcpy(from, to, (sizeof(int)) * size)
#define mid(l, r) (((l) + (r)) >> 1)
#define min Min
#define max Max
#define abs Abs
#define gc getchar()

inline int read()
{
  int x = 0, f = 1;
  char ch = gc;
  while (!isdigit(ch))
  {
    if (ch == '-')
      f = -f;
    ch = gc;
  }
  while (isdigit(ch))
  {
    x = (x << 1) + (x << 3) + (ch - '0');
    ch = gc;
  }
  return x * f;
}
inline void write(int x)
{
  if (x < 0)
    putchar('-'), x = -x;
  if (x / 10)
    write(x / 10);
  putchar('0' + x % 10);
}
template <typename T>
T Abs(T x) { return x < 0 ? -x : x; }
template <typename T, typename TT>
T Min(T x, TT y) { return x < y ? x : y; }
template <typename T, typename TT>
T Max(T x, TT y) { return x > y ? x : y; }

using namespace std;

const int MAXN = 1e9 + 10;

int ppc(int x)
{
  int cnt = 0;
  while ((x & 1) == 0 && x)
  {
    cnt++;
    x >>= 1;
  }
  return cnt;
}
int ctz(int x)
{
  int cnt = 0;
  while (x)
  {
    cnt += (x & 1);
    x >>= 1;
  }
  return cnt;
}

int l, r;
int q;

signed main()
{
#ifndef ONLINE_JUDGE
  freopen("good.in", "r", stdin);
  freopen("good.out", "w", stdout);
#endif
  q = read();
  while (q--)
  {
    l = read(), r = read();
    bool found = false;
    rep(i, l, r, 1) if (ctz(i) == ppc(i))
    {
      write(i), putchar('\n');
      found = true;
      break;
    }
    if (!found)
      puts("-1");
  }
  return 0;
}