#include <iostream>
#include <vector>
using namespace std;
vector<int> v[200005];
int sz[200005],dep[200005],depx;
int pre(int node,int p)
{
    sz[node]=1;
    for (int u:v[node])
    {
        if (u!=p)
        {
            dep[u]=dep[node]+1;
            sz[node]+=pre(u,node);
        }
    }
    return sz[node];
}
vector<int> h;
int query(char c,int u)
{
    printf("%c %d\n",c,u);
    fflush(stdout);
    int ans;
    scanf("%d",&ans);
    return ans;
}
void get(int node)
{
    h.push_back(node);
    int big=-1;
    for (int u:v[node])
    {
        if (sz[node]>sz[u] && (big==-1 || (sz[u]>sz[big])))
        big=u;
    }
    if (big!=-1)
    get(big);
}
int dfs(int node)
{
    h.clear();
    get(node);
    int depy=(depx+dep[h.back()]-query('d',h.back()))/2,y=h[depy-dep[node]];
    if (depx==depy)
    return y;
    return dfs(query('s',y));
}
int main()
{
    int n;
    scanf("%d",&n);
    for (int i=1;i<n;i++)
    {
        int a,b;
        scanf("%d%d",&a,&b);
        v[a].push_back(b);
        v[b].push_back(a);
    }
    depx=query('d',1);
    pre(1,0);
    printf("! %d\n",dfs(1));
    fflush(stdout);
}