diff --git a/logs/app.log b/logs/app.log
new file mode 100644
index 00000000..6ded19ba
--- /dev/null
+++ b/logs/app.log
@@ -0,0 +1,40 @@
+INFO core.basesyntax.Counter:17  Before decrementing, Thread #  3, counter value 20
+INFO core.basesyntax.Counter:20   After decrementing, Thread #  3, counter value 19
+INFO core.basesyntax.Counter:17  Before decrementing, Thread # 20, counter value 19
+INFO core.basesyntax.Counter:20   After decrementing, Thread # 20, counter value 18
+INFO core.basesyntax.Counter:17  Before decrementing, Thread # 19, counter value 18
+INFO core.basesyntax.Counter:20   After decrementing, Thread # 19, counter value 17
+INFO core.basesyntax.Counter:17  Before decrementing, Thread # 16, counter value 17
+INFO core.basesyntax.Counter:20   After decrementing, Thread # 16, counter value 16
+INFO core.basesyntax.Counter:17  Before decrementing, Thread # 18, counter value 16
+INFO core.basesyntax.Counter:20   After decrementing, Thread # 18, counter value 15
+INFO core.basesyntax.Counter:17  Before decrementing, Thread # 17, counter value 15
+INFO core.basesyntax.Counter:20   After decrementing, Thread # 17, counter value 14
+INFO core.basesyntax.Counter:17  Before decrementing, Thread # 15, counter value 14
+INFO core.basesyntax.Counter:20   After decrementing, Thread # 15, counter value 13
+INFO core.basesyntax.Counter:17  Before decrementing, Thread # 11, counter value 13
+INFO core.basesyntax.Counter:20   After decrementing, Thread # 11, counter value 12
+INFO core.basesyntax.Counter:17  Before decrementing, Thread # 13, counter value 12
+INFO core.basesyntax.Counter:20   After decrementing, Thread # 13, counter value 11
+INFO core.basesyntax.Counter:17  Before decrementing, Thread # 14, counter value 11
+INFO core.basesyntax.Counter:20   After decrementing, Thread # 14, counter value 10
+INFO core.basesyntax.Counter:17  Before decrementing, Thread # 12, counter value 10
+INFO core.basesyntax.Counter:20   After decrementing, Thread # 12, counter value  9
+INFO core.basesyntax.Counter:17  Before decrementing, Thread #  8, counter value  9
+INFO core.basesyntax.Counter:20   After decrementing, Thread #  8, counter value  8
+INFO core.basesyntax.Counter:17  Before decrementing, Thread # 10, counter value  8
+INFO core.basesyntax.Counter:20   After decrementing, Thread # 10, counter value  7
+INFO core.basesyntax.Counter:17  Before decrementing, Thread #  9, counter value  7
+INFO core.basesyntax.Counter:20   After decrementing, Thread #  9, counter value  6
+INFO core.basesyntax.Counter:17  Before decrementing, Thread #  7, counter value  6
+INFO core.basesyntax.Counter:20   After decrementing, Thread #  7, counter value  5
+INFO core.basesyntax.Counter:17  Before decrementing, Thread #  6, counter value  5
+INFO core.basesyntax.Counter:20   After decrementing, Thread #  6, counter value  4
+INFO core.basesyntax.Counter:17  Before decrementing, Thread #  2, counter value  4
+INFO core.basesyntax.Counter:20   After decrementing, Thread #  2, counter value  3
+INFO core.basesyntax.Counter:17  Before decrementing, Thread #  5, counter value  3
+INFO core.basesyntax.Counter:20   After decrementing, Thread #  5, counter value  2
+INFO core.basesyntax.Counter:17  Before decrementing, Thread #  4, counter value  2
+INFO core.basesyntax.Counter:20   After decrementing, Thread #  4, counter value  1
+INFO core.basesyntax.Counter:17  Before decrementing, Thread #  1, counter value  1
+INFO core.basesyntax.Counter:20   After decrementing, Thread #  1, counter value  0
diff --git a/src/main/java/core/basesyntax/Counter.java b/src/main/java/core/basesyntax/Counter.java
index 4af46bd4..6e6f86ed 100644
--- a/src/main/java/core/basesyntax/Counter.java
+++ b/src/main/java/core/basesyntax/Counter.java
@@ -4,7 +4,7 @@
 import org.apache.logging.log4j.Logger;
 
 public class Counter {
-    private static final Logger logger = LogManager.getLogger(Counter.class);
+    private static final Logger LOGGER = LogManager.getLogger(Counter.class);
     private static final String MESSAGE = "%20s, Thread # %2s, counter value %2d";
     private int value;
 
@@ -12,11 +12,13 @@ public Counter(int value) {
         this.value = value;
     }
 
-    public void decreaseValue() {
-        logger.info(String.format(MESSAGE,
-                "Before decrementing", Thread.currentThread().getName(), value));
-        value--;
-        logger.info(String.format(MESSAGE,
-                "After decrementing", Thread.currentThread().getName(), value));
+    public synchronized void decreaseValue() {
+        if (value >= 0) {
+            LOGGER.info(String.format(MESSAGE,
+                    "Before decrementing", Thread.currentThread().getName(), value));
+            value--;
+            LOGGER.info(String.format(MESSAGE,
+                    "After decrementing", Thread.currentThread().getName(), value));
+        }
     }
 }