diff --git a/src/20241019/secret/secret_after.cpp b/src/20241019/secret/secret_after.cpp
new file mode 100644
index 0000000..b3cdcbb
--- /dev/null
+++ b/src/20241019/secret/secret_after.cpp
@@ -0,0 +1,48 @@
+
+#include <algorithm>
+#include <cstdlib>
+#include <iomanip>
+#include <ios>
+#include <iostream>
+#include <limits>
+#include <set>
+typedef long long ll;
+
+const ll max_n = 1e5+5;
+ll n, q, input,now;
+char c;
+std::set<ll> pos;
+
+#define NV(v)#v<<" : "<<(v)
+
+int main(){
+    freopen("secret.in", "r", stdin);
+    freopen("secret.out", "w", stdout);
+
+    std::cin>>n>>q;
+    for(ll _{0};_<n;_++){
+        std::cin>>input;
+        pos.insert(input);
+    }
+    for(ll _{0};_<q;_++){
+        std::cin>>c>>now;
+
+        if(c=='+'){
+            pos.insert(now);
+        }else if(c=='-'){
+            pos.erase(now);
+        }else{
+            double ans = std::numeric_limits<decltype(ans)>::max();
+            const auto it_right {pos.upper_bound(now)};
+            if ( it_right != pos.end()){
+                ans = std::min(ans, (double)std::max(*pos.rbegin()-now, *it_right - *pos.begin()) / (double)2.0 );
+            }
+            auto it_left {pos.find(now)};
+            if(it_left!=pos.begin()){
+                --it_left;
+                ans = std::min(ans, (double)std::max(*pos.rbegin() - *it_left, now - *pos.begin()) / (double)2.0 );
+            }
+            std::cout<<std::fixed<<std::setprecision(2)<<ans<<'\n';
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/20241019/secret/secret_web.cpp b/src/20241019/secret/secret_web.cpp
new file mode 100644
index 0000000..e112791
--- /dev/null
+++ b/src/20241019/secret/secret_web.cpp
@@ -0,0 +1,52 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+using ll = long long;
+
+set<ll>s;
+set<ll>::iterator it;
+int main()
+{
+    freopen("secret.in","r",stdin);
+    freopen("secret.out","w",stdout);
+    ll n,q,x,i;
+    double ans;
+    char pd;
+    cin>>n>>q;
+    for(i=1;i<=n;i++)
+    {
+        cin>>x;
+        s.insert(x);
+    }
+    for(i=1;i<=q;i++)
+    {
+        cin>>pd>>x;
+        if(pd=='+')
+        {
+            s.insert(x);
+        }
+        if(pd=='-')
+        {
+            s.erase(x);
+        }
+        if(pd=='?')
+        {
+            ans=0x7f7f7f7f;
+            it=s.upper_bound(x);
+            if(it!=s.end())
+            {
+                ans=min(ans,max(*it-*s.begin(),*(--s.end())-x)/2.0);
+            }
+            it=s.find(x);
+            if(it!=s.begin())
+            {
+                it=prev(it);
+                ans=min(ans,max(x-*s.begin(),*(--s.end())-*it)/2.0);
+            }
+            printf("%.2lf\n",ans);
+        }	
+    }
+    fclose(stdin);
+    fclose(stdout);	
+    return 0;
+}
\ No newline at end of file