#include <bits/stdc++.h>
using namespace std;
const int MOD = 1000000007;
const double pi = atan(1.0) * 4.0;
const double eps = 1e-8;
long long gcd(long long x, long long y) { return y ? gcd(y, x % y) : x; }
int bc(int n) { return n ? bc((n - 1) & n) + 1 : 0; }
const int N = 1000005;
int i, j, k, m, n;
int ans;
vector<int> adj[N];
int dead[N], sz[N], h[N], pr[N];
int dist(int u) {
  cout << "d " << u << endl;
  int ret;
  cin >> ret;
  return ret;
}
int sub(int u) {
  cout << "s " << u << endl;
  int ret;
  cin >> ret;
  return ret;
}
void over(int u) {
  cout << "! " << u << endl;
  exit(0);
}
void dfs(int i, int par) {
  sz[i] = 1;
  for (int j : adj[i])
    if (j != par && !dead[j]) {
      pr[j] = i;
      h[j] = h[i] + 1;
      dfs(j, i);
      sz[i] += sz[j];
    }
}
int main() {
  int tn = 1;
  for (int tt = 1; tt <= tn; tt++) {
    cin >> n;
    for (int k = 0; k < n - 1; k++) {
      cin >> i >> j;
      adj[i].push_back(j);
      adj[j].push_back(i);
    }
    int d = dist(1);
    int root = 1;
    while (1) {
      if (d == 0) over(root);
      h[root] = 0;
      dfs(root, -1);
      int oc = -1;
      for (int j : adj[root])
        if (!dead[j]) {
          if (oc == -1)
            oc = j;
          else
            oc = -2;
        }
      if (oc > 0) {
        root = oc;
        d--;
        continue;
      }
      int y = root;
      int sg = 1;
      while (sg) {
        sg = 0;
        for (int j : adj[y])
          if (!dead[j] && h[j] == h[y] + 1 && 2 * sz[j] + 1 >= sz[root]) {
            y = j;
            sg = 1;
            break;
          }
      }
      if (y == root) {
        dead[root] = 1;
        root = sub(y);
        d--;
      } else {
        int d2 = dist(y);
        if (d2 == 0) over(y);
        if (h[y] + d2 == d) {
          root = y;
          dead[pr[root]] = 1;
          d = d2;
        } else {
          dead[y] = 1;
        }
      }
    }
  }
  return 0;
}
