diff --git a/src/SignedInteger.java b/src/SignedInteger.java
new file mode 100644
index 0000000..5c32f28
--- /dev/null
+++ b/src/SignedInteger.java
@@ -0,0 +1,30 @@
+public class SignedInteger {
+
+    int n;
+    boolean isNegative;
+
+    public SignedInteger(int n){
+        isNegative = n < 0;
+        this.n = Math.abs(n);
+    }
+
+    int getValue(){
+        return isNegative ? -n : n;
+    }
+
+    void setValue(int n){
+        isNegative = n < 0;
+        this.n = Math.abs(n);
+    }
+
+    void addValue(int n){
+        this.n += isNegative ? -n : n;
+        if(this.n < 0){
+            isNegative = !isNegative;
+            this.n = Math.abs(this.n);
+        }
+    }
+
+}
+
+