diff --git a/khj20006/202503/21 BOJ G4 Jigsaw of Shadows.md b/khj20006/202503/21 BOJ G4 Jigsaw of Shadows.md
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+```cpp
+
+#include <bits/stdc++.h>
+using namespace std;
+
+using ld = long double;
+
+int main(){
+  cin.tie(0)->sync_with_stdio(0);
+  
+  int theta, N;
+  cin>>theta>>N;
+  vector<pair<int,int>> A(N);
+  for(auto &[x,h]:A) cin>>x>>h;
+  sort(A.begin(), A.end());
+  
+  ld t = tan(M_PI * theta / 180.);
+  ld ans = 0, last = -1;
+  for(int i=0;i<N;i++){
+    int x = A[i].first, h = A[i].second;
+    ld pos = (ld)h / t;
+    if(last > pos+x) continue;
+    if(last > x) ans += pos+x-last;
+    else ans += pos;
+    last = pos+x;
+  }
+  cout<<ans;
+  
+}
+
+```