#include <bits/stdc++.h>
using namespace std;
int queryD(int node) {
  cout << "d " << node << "\n";
  fflush(stdin);
  int ans;
  cin >> ans;
  return ans;
}
int second[200002];
int queryS(int node) {
  if (second[node] != 0) return second[node];
  cout << "s " << node << "\n";
  fflush(stdin);
  int ans;
  cin >> ans;
  return second[node] = ans;
}
void answer(int node) {
  cout << "! " << node << "\n";
  fflush(stdout);
}
int n;
int droot;
vector<int> edges[200002];
bool visited[200002];
vector<int> sons[200002];
int level[200002];
int cnt[200002];
int total;
void dfs(int node) {
  visited[node] = true;
  for (int u : edges[node])
    if (visited[u] == false) {
      level[u] = level[node] + 1;
      dfs(u);
      sons[node].push_back(u);
    }
}
bool out[200002];
void compute(int node) {
  cnt[node] = 0;
  if (level[node] == droot) {
    cnt[node] = 1;
    total++;
  }
  for (int u : sons[node])
    if (out[u] == false) {
      compute(u);
      cnt[node] += cnt[u];
    }
}
int root = 1;
bool solve(int node) {
  if (level[node] == droot && total == 1) {
    answer(node);
    return true;
  }
  if (cnt[node] * 2 <= total) {
    int d = queryD(node);
    if (d == 0) {
      answer(node);
      return true;
    }
    if (d + level[node] > droot) {
      out[node] = true;
      total = 0;
      compute(root);
    } else {
      root = node;
      total -= cnt[node];
    }
    return false;
  }
  if (sons[node].size() == 1 && node == root) root = sons[node][0];
  if (node == root && sons[node].size() > 30) {
    int u = queryS(node);
    return solve(u);
  }
  int umx = 0;
  for (int u : sons[node])
    if (out[u] == false) {
      if (cnt[u] > cnt[umx]) umx = u;
    }
  if (umx == 0) return true;
  return solve(umx);
}
int main() {
  cin >> n;
  for (int i = 1; i < n; i++) {
    int u, v;
    cin >> u >> v;
    edges[u].push_back(v);
    edges[v].push_back(u);
  }
  dfs(1);
  droot = queryD(1);
  if (droot == 0) {
    answer(1);
    return 0;
  }
  if (sons[1].size() == n - 1) {
    answer(queryS(1));
    return 0;
  }
  compute(1);
  while (solve(root) == false)
    ;
  return 0;
}
