diff --git a/src/main/java/fr/pandacube/java/external_tools/Main.java b/src/main/java/fr/pandacube/java/external_tools/Main.java
new file mode 100644
index 0000000..ea3e0bc
--- /dev/null
+++ b/src/main/java/fr/pandacube/java/external_tools/Main.java
@@ -0,0 +1,121 @@
+package fr.pandacube.java.external_tools;
+
+import java.io.FileReader;
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Objects;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
+
+public class Main {
+	
+	
+	static class Row {
+		int rowid;
+		String date, user, uuid;
+		int wid, x, y, z, type, amount, action;
+		boolean rolled_back;
+	}
+	
+	
+	
+	static class Chest {
+		final int wid, x, y, z, hashCode;
+		List<Row> sources = new ArrayList<>();
+		int actualCount = 0;
+		boolean alreadyRolledBack = false;
+		public Chest(int w, int wx, int wy, int wz) {
+			wid = w;
+			x = wx;
+			y = wy;
+			z = wz;
+			hashCode = Objects.hash(wid, x, y, z);
+		}
+		
+		@Override
+		public boolean equals(Object o) {
+			if (o == null || !(o instanceof Chest))
+				return false;
+			Chest c = (Chest) o;
+			return wid == c.wid && x == c.x && y == c.y && z == c.z;
+		}
+		
+		@Override
+		public int hashCode() {
+			return hashCode;
+		}
+		
+		@Override
+		public String toString() {
+			return "world=" + wid + " - /tppos " + x + " " + y + " " + z + " - rolledBack=" + alreadyRolledBack + " - amount=" + actualCount;
+		}
+		
+		public String toCSVString() {
+			return wid + "," + x + "," + y + "," + z + "," + alreadyRolledBack + "," + actualCount;
+		}
+	}
+	
+	
+	
+	
+	public static void main(String args[]) throws Exception {
+		
+		/*CSVParser parser = new CSVParser(new FileReader("co_survie_container.csv"), CSVFormat.DEFAULT);
+		
+		
+		List<Row> rows = StreamSupport.stream(parser.spliterator(), false).map(r -> {
+			Row ret = new Row();
+			ret.rowid = Integer.parseInt(r.get(0));
+			ret.date = r.get(1);
+			ret.user = r.get(2);
+			ret.uuid = r.get(3);
+			ret.wid = Integer.parseInt(r.get(4));
+			ret.x = Integer.parseInt(r.get(5));
+			ret.y = Integer.parseInt(r.get(6));
+			ret.z = Integer.parseInt(r.get(7));
+			ret.type = Integer.parseInt(r.get(8));
+			ret.amount = Integer.parseInt(r.get(9));
+			ret.action = Integer.parseInt(r.get(10));
+			ret.rolled_back = r.get(11).equals("1");
+			return ret;
+		}).collect(Collectors.toList());
+		
+		rows.sort(Comparator.comparingInt(r -> r.rowid));
+		
+		List<Chest> chests = new ArrayList<>();
+		
+		
+		
+		for (Row row : rows) {
+			Chest c = new Chest(row.wid, row.x, row.y, row.z);
+			int idx = chests.indexOf(c);
+			c = (idx >= 0) ? chests.get(idx) : c;
+			if (idx < 0) {
+				chests.add(c);
+				idx = chests.size() - 1;
+			}
+			
+			c.sources.add(row);
+			
+			if (row.rolled_back)
+				c.alreadyRolledBack = true;
+			
+			if (!c.alreadyRolledBack) {
+				c.actualCount += (row.action == 1) ? row.amount : -row.amount;
+				if (c.actualCount == 0) {
+					chests.remove(idx);
+				}
+			}
+			
+		}
+		
+		
+		
+		chests.sort(Comparator.comparingInt(c -> c.actualCount));
+		
+		chests.forEach(c -> System.out.println(c.toCSVString()));
+		*/
+		
+	}
+}
\ No newline at end of file
diff --git a/src/main/java/fr/pandacube/java/util/RandomUtil.java b/src/main/java/fr/pandacube/java/util/RandomUtil.java
index cc0bd1d..a53d1bb 100644
--- a/src/main/java/fr/pandacube/java/util/RandomUtil.java
+++ b/src/main/java/fr/pandacube/java/util/RandomUtil.java
@@ -1,5 +1,6 @@
 package fr.pandacube.java.util;
 
+import java.util.List;
 import java.util.Random;
 
 public class RandomUtil {
@@ -13,5 +14,13 @@ public class RandomUtil {
 	public static double nextDoubleBetween(double minInclu, double maxExclu) {
 		return rand.nextDouble() * (maxExclu - minInclu) + minInclu;
 	}
+	
+	public static <T> T arrayElement(T[] arr) {
+		return arr[rand.nextInt(arr.length)];
+	}
+	
+	public static <T> T listElement(List<T> arr) {
+		return arr.get(rand.nextInt(arr.size()));
+	}
 
 }
diff --git a/src/main/java/fr/pandacube/java/util/StringUtil.java b/src/main/java/fr/pandacube/java/util/StringUtil.java
index 665c56b..c599f0b 100644
--- a/src/main/java/fr/pandacube/java/util/StringUtil.java
+++ b/src/main/java/fr/pandacube/java/util/StringUtil.java
@@ -1,5 +1,7 @@
 package fr.pandacube.java.util;
 
+import java.util.List;
+
 public class StringUtil {
 	public static String formatDouble(double d) {
 		if (d == (long) d)
@@ -19,4 +21,12 @@ public class StringUtil {
 			if (c == c_match) count++;
 		return count;
 	}
+	
+	
+	
+	
+	public static String joinGrammatically(CharSequence sep1, CharSequence sepFinal, List<String> strings) {
+	    int size = strings == null ? 0 : strings.size();
+	    return size == 0 ? "" : size == 1 ? strings.get(0) : String.join(sep1, strings.subList(0, --size)) + sepFinal + strings.get(size);
+	}
 }