diff --git a/Appendix C/solutions/2064.cpp b/Appendix C/solutions/2064.cpp
index 6c991660..9250e415 100644
--- a/Appendix C/solutions/2064.cpp	
+++ b/Appendix C/solutions/2064.cpp	
@@ -1,11 +1,34 @@
-// Authored by : BaaaaaaaaaaarkingDog
+// Authored by : uhwan0723
 // Co-authored by : -
-// http://boj.kr/****************
+// http://boj.kr/7537647dfa6d4aeabf0599060c0c1c3f
 #include <bits/stdc++.h>
 using namespace std;
 
+int n, bytes[4];
+unsigned int mask, mx = 0, mn = 0xFFFFFFFF;
+
+void print(unsigned int addr){
+  for(int i = 0; i < 4; ++i)
+    bytes[i] = (addr >> i*8) & ((1 << 8) - 1);
+  printf("%d.%d.%d.%d\n", bytes[3], bytes[2], bytes[1], bytes[0]);
+}
+
 int main(void){
-  ios::sync_with_stdio(0);
-  cin.tie(0);
-  
-}
\ No newline at end of file
+  scanf("%d", &n);
+  while(n--){
+    scanf("%d.%d.%d.%d", bytes+3, bytes+2, bytes+1, bytes);
+    unsigned int ip = 0;
+    for(int i = 0; i < 4; ++i)
+      ip |= (bytes[i] << i*8);
+    mx = max(mx, ip);
+    mn = min(mn, ip);
+  }
+  mask = ~(mx ^ mn);
+  for(int i = 31; i >= 0; --i){
+    if(((mask >> i) & 1) == 1) continue;
+    mask = (mask >> i) << i;
+    break;
+  }
+  print(mx & mask);
+  print(mask);
+}