#include <bits/stdc++.h>
using namespace std;
long long fS(long long x) {
  long long lo = 1, hi = x - 1, cn = 0, ans = -1, out = 1;
  while (cn <= 80) {
    if (cn & 1)
      ans -= (lo + hi) / 2;
    else
      ans += (lo + hi) / 2;
    lo = (lo + hi) / 2 + 1;
    out = min(out, ans);
    cn++;
  }
  return out;
}
int main() {
  int t;
  cin >> t;
  while (t--) {
    long long n;
    cin >> n;
    long long start = -fS(n);
    cout << "? " << start << endl;
    long long tr;
    cin >> tr;
    long long lo = 1LL, hi = n - 1LL, cn = 0LL, best = n, ans = start, x;
    while (lo <= hi) {
      long long mid = (lo + hi) / 2LL;
      if (cn & 1)
        ans -= mid;
      else
        ans += mid;
      cout << "? " << ans << endl;
      cin >> x;
      if (x) {
        hi = mid - 1LL;
        best = mid;
      } else {
        lo = mid + 1LL;
      }
      cn++;
    }
    cout << "= " << best << endl;
  }
}
