diff --git a/src/CSP-S2020/zoo/zoo.cpp b/src/CSP-S2020/zoo/zoo.cpp
new file mode 100644
index 0000000..ecc3247
--- /dev/null
+++ b/src/CSP-S2020/zoo/zoo.cpp
@@ -0,0 +1,52 @@
+#include <bitset>
+#include <iostream>
+
+using ull = unsigned long long;
+
+ull n, m, c, k, input, _;
+const ull max_k = 64+5;
+// const ull max_n = 1e6+5;
+ull used_bits;
+std::bitset<max_k> vis_bits;
+
+#define NV(v)#v<<" : "<<(v)
+
+#ifdef ONLINE_JUDGE
+    #define DEBUG(code)
+#else
+    #define DEBUG(code)code
+#endif
+
+int main(){
+    
+    
+    std::iostream::sync_with_stdio(false), std::cin.tie(nullptr), std::cout.tie(nullptr);
+
+    std::cin>>n>>m>>c>>k;
+
+    if(n==0 && m==0 && k==64){
+        std::cout<<"18446744073709551616\n";
+        return 0;
+    }
+
+    for(ull i{1};i<=n;i++){
+        std::cin>>input;
+        DEBUG(std::cout<<NV(input)<<" ";)
+        DEBUG(std::cout<<NV(std::bitset<4>(input))<<" ";)
+        used_bits |= input;
+        DEBUG(std::cout<<'\n';)
+    }
+    for(ull i{1};i<=m;i++){
+        std::cin>>input>>_;
+        if(!((used_bits>>input)&1) && vis_bits[input]==false){
+            DEBUG(std::cout<<"unused_bit++ ;"<<NV(input)<<'\n';)
+            k--;
+            vis_bits[input] = true;
+        }
+    }
+    const auto left_shift = [](const ull n, const ull num)->ull{
+        return num < 64 ? n<<num : 0;
+    };
+    DEBUG(std::cout<<NV(k)<<'\n';)
+    std::cout<<(left_shift(1, k)) - n<<'\n';
+}
\ No newline at end of file
diff --git a/src/P7913/P7913.cpp b/src/P7913/P7913.cpp
new file mode 100644
index 0000000..f14bfc3
--- /dev/null
+++ b/src/P7913/P7913.cpp
@@ -0,0 +1,30 @@
+#include <iostream>
+using ll = long long;
+
+template<class ...Args>
+void read(Args&...args){
+    (std::cin>>...>>args);
+}
+
+template<class ...Args>
+void print(const Args&...args){
+    (std::cout<<...<<args);
+}
+
+const ll max_m = 1e5;
+ll n, m1, m2, arr1[max_m], arr2[max_m];
+
+
+int main(){
+    read(n,m1,m2);
+    for(ll i{1};i<=m1;i++){
+        ll a,b;
+        read(a, b);
+
+    }
+    for(ll i{1};i<=m2;i++){
+        ll a, b;
+        read(a, b);
+        
+    }
+}
\ No newline at end of file