#include <bits/stdc++.h>
using namespace std;
vector<int> g[200005];
bool mk[200005], mk2[200005], ok[200005];
int p[200005], l[200005], sons[200005][2];
void dfs(int u) {
  mk[u] = 1;
  for (auto y : g[u])
    if (!mk[y] && !mk2[y]) {
      l[y] = l[u] + 1;
      dfs(y);
      p[y] = u;
    }
}
void dfs1(int u) {
  mk[u] = 1;
  if (ok[u]) sons[u][0]++;
  for (auto y : g[u])
    if (!mk[y] && !mk2[y]) {
      dfs1(y);
      sons[u][0] += sons[y][0];
      sons[u][1] = max(sons[y][0], sons[u][1]);
    }
}
int main() {
  int n, u, v;
  cin >> n;
  for (int i = 0; i < n - 1; i++) {
    cin >> u >> v;
    u--, v--;
    g[u].push_back(v);
    g[v].push_back(u);
  }
  p[0] = -1;
  dfs(0);
  cout << "d 1" << '\n';
  cout.flush();
  int level;
  cin >> level;
  int cont = 0;
  for (int i = 0; i < n; i++)
    if (l[i] == level) {
      ok[i] = 1;
      cont++;
    }
  for (int i = 0; i < n; i++) mk[i] = 0;
  int r = 0;
  while (cont > 1) {
    dfs1(r);
    for (int i = 0; i < n; i++)
      if (sons[i][0] > cont / 2 && sons[i][1] <= cont / 2) {
        cout << "d" << ' ' << i + 1 << '\n';
        cout.flush();
        int x;
        cin >> x;
        if (x == level - l[i]) {
          mk2[i] = 1;
          cout << "s" << ' ' << i + 1 << '\n';
          cout.flush();
          cin >> r;
          r--;
          cont = sons[r][0];
        } else {
          mk2[i] = 1;
          cont -= sons[i][0];
        }
        break;
      }
    for (int i = 0; i < n; i++) mk[i] = sons[i][0] = sons[i][1] = 0;
  }
  dfs1(r);
  for (int i = 0; i < n; i++)
    if (mk[i] && ok[i]) {
      cout << "! " << i + 1 << '\n';
      break;
    }
  return 0;
}
