diff --git a/bitcoin-project/src/main.cpp b/bitcoin-project/src/main.cpp
index 7e19e39..763b38f 100644
--- a/bitcoin-project/src/main.cpp
+++ b/bitcoin-project/src/main.cpp
@@ -1,5 +1,6 @@
 #include <iostream>
 #include "csv_loader.hpp"
+#include "utils.hpp"
 
 int main() {
     auto records = load_csv("data/data.csv");
@@ -14,4 +15,13 @@ int main() {
                   << records[i].close << " "
                   << records[i].volume << "\n";
     }
+
+    auto days = group_by_day(records);
+    std::cout << "Total days: " << days.size() << "\n";
+
+    auto parts = split_days(days, 4);
+
+    for (int i = 0; i < 4; i++) {
+        std::cout << "Part " << i << " has " << parts[i].size() << " days:\n";
+    }
 }
diff --git a/bitcoin-project/src/utils.cpp b/bitcoin-project/src/utils.cpp
new file mode 100644
index 0000000..aa78e7f
--- /dev/null
+++ b/bitcoin-project/src/utils.cpp
@@ -0,0 +1,25 @@
+#include "utils.hpp"
+
+std::map<DayIndex, std::vector<Record>> group_by_day(const std::vector<Record>& recs) {
+    std::map<DayIndex, std::vector<Record>> days;
+
+    for (const auto& r : recs) {
+        DayIndex day = static_cast<DayIndex>(r.timestamp) / 86400;
+        days[day].push_back(r);
+    }
+
+    return days;
+}
+
+std::vector<std::vector<DayIndex>> split_days(const std::map<DayIndex, std::vector<Record>>& days, int parts) {
+    std::vector<std::vector<DayIndex>> out(parts);
+
+    int i = 0;
+    for (auto& kv : days) {
+        out[i % parts].push_back(kv.first);
+        i++;
+    }
+
+    return out;
+}
+
diff --git a/bitcoin-project/src/utils.hpp b/bitcoin-project/src/utils.hpp
new file mode 100644
index 0000000..515acfd
--- /dev/null
+++ b/bitcoin-project/src/utils.hpp
@@ -0,0 +1,11 @@
+#pragma once
+
+#include "record.hpp"
+#include <map>
+#include <vector>
+
+using DayIndex = long long;
+
+std::map<DayIndex, std::vector<Record>> group_by_day(const std::vector<Record>& recs);
+std::vector<std::vector<DayIndex>> split_days(const std::map<DayIndex, std::vector<Record>>& days, int parts);
+