diff --git a/res/2015/day25/test_input.txt b/res/2015/day25/test_input.txt
index e69de29..1b7db61 100644
--- a/res/2015/day25/test_input.txt
+++ b/res/2015/day25/test_input.txt
@@ -0,0 +1 @@
+To continue, please consult the code grid in the manual.  Enter the code at row 3, column 4.
diff --git a/src/2015/Day25.cpp b/src/2015/Day25.cpp
index 4a7d6b8..d65d724 100644
--- a/src/2015/Day25.cpp
+++ b/src/2015/Day25.cpp
@@ -2,26 +2,33 @@
 
 namespace y2015::day25
 {
-  REGISTER_DAY(2015, Day25, std::vector<int>, int);
+  using Pair = std::pair<int, int>;
+  REGISTER_DAY(2015, Day25, Pair, int);
 
-  REGISTER_TEST_EXAMPLE(2015, Day25, ExampleInput, 1, 0);
-  REGISTER_TEST(2015, Day25, Input, 1, 0);
+  REGISTER_TEST_EXAMPLE(2015, Day25, ExampleInput, 1, 7981243);
+  REGISTER_TEST(2015, Day25, Input, 1, 8997277);
   REGISTER_TEST_EXAMPLE(2015, Day25, ExampleInput, 2, 0);
   REGISTER_TEST(2015, Day25, Input, 2, 0);
 
   READ_INPUT(input)
   {
-    std::vector<int> vec;
-    std::string str;
-    while (getline(input, str))
-    {
-    }
-    return vec;
+    int i1;
+    int i2;
+    input >> "To continue, please consult the code grid in the manual.  Enter the code at row " >> i2 >> ", column " >>
+      i1;
+
+    return std::pair{i1, i2};
+  }
+
+  int GetPower(const std::pair<int, int>& coordinate)
+  {
+    return (coordinate.first + coordinate.second - 1) * (coordinate.first + coordinate.second - 1 + 1) / 2 + 1 -
+           coordinate.second;
   }
 
   OUTPUT1(input)
   {
-    return 0;
+    return Helper::FastExponentiation(20151125, 252533, GetPower(input) - 1, 33554393);
   }
 
   OUTPUT2(input)
diff --git a/src/common/lib/Graph.h b/src/common/lib/Graph.h
index 79cb8f7..92d1e17 100644
--- a/src/common/lib/Graph.h
+++ b/src/common/lib/Graph.h
@@ -2,6 +2,7 @@
 
 #include <map>
 #include <set>
+#include <vector>
 
 template <typename Key, typename Value>
 class Graph
diff --git a/src/common/lib/Helper.h b/src/common/lib/Helper.h
index 0d7cf41..19a529b 100644
--- a/src/common/lib/Helper.h
+++ b/src/common/lib/Helper.h
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <stdint.h>
+
 #include <algorithm>
 #include <array>
 #include <functional>
@@ -607,6 +609,24 @@ struct Helper
     return currentRes;
   }
 
+  static uint64_t FastExponentiation(uint64_t start, uint64_t multiplication, uint64_t power, uint64_t mod)
+  {
+    while (power > 0)
+    {
+      if (power % 2 == 0)
+      {
+        multiplication = (multiplication * multiplication) % mod;
+        power /= 2;
+      }
+      else
+      {
+        start = (start * multiplication) % mod;
+        power--;
+      }
+    }
+    return start;
+  }
+
   // Input    - Puzzle input
   // Function - bool(int64_t);
   //            Given index, return whether the index should increase next
diff --git a/src/common/lib/Json.h b/src/common/lib/Json.h
index 569e740..7066d2f 100644
--- a/src/common/lib/Json.h
+++ b/src/common/lib/Json.h
@@ -388,7 +388,7 @@ public:
     else if (json.IsInt())
       os << json.GetInt64();
     else if (json.IsBool())
-      os << json.GetBool() ? "true" : "false";
+      os << (json.GetBool() ? "true" : "false");
     else if (json.IsNull())
       os << "null";
     return os;
diff --git a/src/common/lib/JsonUtil.cpp b/src/common/lib/JsonUtil.cpp
index 3c28380..c2408a1 100644
--- a/src/common/lib/JsonUtil.cpp
+++ b/src/common/lib/JsonUtil.cpp
@@ -1,7 +1,6 @@
 #include "JsonUtil.h"
 
 #include <cstring>
-#include <utility>
 
 #include "Json.h"