#include <bits/stdc++.h>
using namespace std;
const long long int MOD = 1000000007;
const long long BIG = 1446803456761533460;
const int Big = 336860180;
stringstream sss;
const long long int maxn = 200010;
long long int n;
vector<long long int> g[maxn];
long long int sz[maxn];
long long int ht[maxn];
long long int pars[maxn];
bool vis[maxn];
void dfs_ht(long long int x, long long int par) {
  pars[x] = par;
  for (auto y : g[x]) {
    if (y != par) {
      ht[y] = ht[x] + 1;
      dfs_ht(y, x);
    }
  }
}
void dfs_sz(long long int x, long long int par) {
  sz[x] = 1;
  for (auto y : g[x]) {
    if (y != par && !vis[y]) {
      dfs_sz(y, x);
      sz[x] += sz[y];
    }
  }
}
long long int centroid(long long int x, long long int par, long long int szt) {
  for (auto y : g[x]) {
    if (y != par && !vis[y] && sz[y] * 2 > szt) {
      return centroid(y, x, szt);
    }
  }
  return x;
}
void MAIN() {
  cin >> n;
  for (long long int i = (0); i < (n - 1); ++i) {
    long long int a, b;
    cin >> a >> b;
    g[a].push_back(b), g[b].push_back(a);
  }
  dfs_ht(1, 0);
  long long int hx;
  cout << "d 1\n";
  cout.flush();
  cin >> hx;
  long long int v = 1;
  while (true) {
    dfs_sz(v, 0);
    if (sz[v] == 1) {
      cout << "! " << v << '\n';
      break;
    }
    long long int c = centroid(v, 0, sz[v]);
    vis[c] = true;
    v = pars[c];
    cout << "d " << c << '\n';
    long long int d;
    cout.flush();
    cin >> d;
    if (d == 0) {
      cout << "! " << c << '\n';
      break;
    }
    if (hx == ht[c] + d) {
      cout << "s " << c << '\n';
      cout.flush();
      cin >> v;
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  cout << fixed << setprecision(10);
  sss << R"(
5
1 2
1 3
3 4
3 5
    )";
  MAIN();
  return 0;
}
