import System;

var result : double;
var args : String[] = Environment.GetCommandLineArgs();
try {
	if(args.Length != 4)
		throw(1);
	var a : int = Convert.ToInt32(args[1]);
	var b : int = Convert.ToInt32(args[3]);
	var op = args[2];
	if(op == "+")
		result = a + b;
	else if(op == "-")
		result = a - b;
	else if(op == "*")
		result = a * b;
	else if(op == "/")
		result = a / b;
	else
		throw(1);
}
catch(e : int) {
	print("usage : " + args[0] + " num1 op num2");
	print("op : '+', '-', '*', '/'");
	Environment.Exit(1);
}
catch(e : System.FormatException) {
	print("エラー : 2番目と4番目の引数は整数");
	Environment.Exit(1);
}
print(result);