using System;
using System.Collections;
using System.Text;
using System.Text.RegularExpressions;

class Program
{
	static void Main()
	{
		foreach(string s in new string[] {
				"1 + 23",					// 24
				"50 + 2 * 5",				// 60
				"( 5 + 2 ) * 3",			// 21
				"3 * ( 5 + 2 )",			// 21
				"-3 + 4",					// 1
				"3 + -4",					// -1
				"-3 + -4",					// -7
				"-3 - -4",					// 1
				"-3 * -4",					// 12
				"-5 + 2 * 5",				// 5
				"5 + 2 * -5",				// -5
				"((5 + 1) * 8 - 4) / 2",	// 22
				"-( 5 + 2 ) * 3",			// -21
				"3 * -( 5 + 2 )",			// -21
				"10 % 3 ",					// 1
				"10 * 0.5",					// 5
				"+10 * - 0 . 025",			// -0.25
			})
		{
			Console.WriteLine("Eval: {0} = {1}", s, Eval(s));
		}
	}

	// 計算式を評価
	public static decimal Eval(string str)
	{
		CharEnumerator e = Split(str);
		return e.MoveNext() ? EvalAddition(e) : 0;
	}

	// 文字分割、ゴミ排除
	static CharEnumerator Split(string str)
	{
		StringBuilder sb = new StringBuilder();
		foreach(Match m in new Regex(@"[\(\)\+\-\*\/\%\.0-9]").Matches(str))
			sb.Append(m.Value);
		return sb.ToString().GetEnumerator();
	}

	// 加法式を評価
	static decimal EvalAddition(CharEnumerator factor)
	{
		decimal value = EvalMultiplication(factor);
		while(true)
		{
			char op = new char();
			try { op = factor.Current; }
			catch(InvalidOperationException) { break; }
			if(!(op == '+' || op == '-')) break;
			if(!factor.MoveNext()) break; // 式が途中半端？
			decimal val = EvalMultiplication(factor);

			switch(op)
			{
				case '+': value += val; break;
				case '-': value -= val; break;
			}
		}
		return value;
	}

	// 乗法式を評価
	static decimal EvalMultiplication(CharEnumerator factor)
	{
		decimal value = EvalExpression(factor);
		while(true)
		{
			char op = new char();
			try { op = factor.Current; }
			catch(InvalidOperationException) { break; }
			if(!(op == '*' || op == '/' || op == '%')) break;
			if(!factor.MoveNext()) break; // 式が途中半端？
			decimal val = EvalExpression(factor);
			switch(op)
			{
				case '*': value *= val; break;
				case '/': value /= val; break;
				case '%': value %= val; break;
			}
		}
		return value;
	}

	// 単項式の評価(処理的に基本式含む)
	static decimal EvalExpression(CharEnumerator factor)
	{
		decimal value = 1;
		if(char.IsDigit(factor.Current))
		{
			StringBuilder sb = new StringBuilder();
			sb.Append(factor.Current);
			while(factor.MoveNext())
			{
				if(char.IsDigit(factor.Current) || factor.Current == '.')
					sb.Append(factor.Current);
				else
					break;
			}
			if(!decimal.TryParse(sb.ToString(), out value)) value = 1;
		}
		else if(factor.Current == '+')
		{
			value = factor.MoveNext() ? EvalExpression(factor) : 1;
		}
		else if(factor.Current == '-')
		{
			value = factor.MoveNext() ? EvalExpression(factor) * -1 : 1;
		}
		else if(factor.Current == '(')
		{
			value = factor.MoveNext() ? EvalAddition(factor) : 1;
			if(factor.Current == ')') { factor.MoveNext(); }
			else { } // )以外はこないはず…
		}
		return value;
	}
}