first try

Module1/Lexer.cs

@@ -68,13 +68,18 @@ namespace Lexer
         public override bool Parse()
         {
             NextCh();
+			int res = 0; //    
+			int sign = 1; //  
             if (currentCh == '+' || currentCh == '-')
             {
+				if (currentCh == '-')
+					sign = -1;
                 NextCh();
             }
         
             if (char.IsDigit(currentCh))
             {
+				res = currentCh - '0';
                 NextCh();
             }
             else
@@ -84,6 +89,7 @@ namespace Lexer
 
             while (char.IsDigit(currentCh))
             {
+				res = res * 10 + currentCh - '0';
                 NextCh();
             }
 
@@ -93,6 +99,8 @@ namespace Lexer
                 Error();
             }
 
+			this.parseResult = res * sign;
+
             return true;
 
         }
@@ -113,10 +121,40 @@ namespace Lexer
             builder = new StringBuilder();
         }
 
-        public override bool Parse()
-        { 
-            throw new NotImplementedException();
-        }
+		public override bool Parse()
+		{
+			NextCh();
+
+			if (currentCharValue != -1)
+			{
+				Error();
+			}
+
+			var builder1 = new StringBuilder();
+
+			if (char.IsLetter(currentCh) || currentCh == '_')
+			{
+				builder1.Append(currentCh);
+				NextCh();
+			}
+			else
+				Error();
+
+			while (char.IsDigit(currentCh) || char.IsLetter(currentCh) || currentCh == '_')
+			{
+				builder1.Append(currentCh);
+				NextCh();
+			}
+
+			if (currentCharValue != -1)
+			{
+				Error();
+			}
+
+			parseResult = builder1.ToString();
+
+			return true;
+		}
        
     }