[求助]哪位请指点一下我错在哪里，谢谢！

我是初学者，安装了dev c++的开发工具，但是使用起来偶尔会出问题。即按照书本的案例编写的程序，仔细检查了几遍，和书上的一样，但是运行时仍会提示错误，该如何是好？

#include <iostream>

int Doubler(int AmountToDouble);

int main()
{
using std::cout;

int result = 0;
int input;

cout << "Enter a number between 0 and 10,000 to double:";
std::cin >> input;

cout << "\nBefore doubler is called...";
cout << "\ninput:" << input << " doubled:" << result << "\n";

result = Doubler(input);

cout << "\Back from Doubler...\n";
cout << "\ninput:" << input << " doubled:" << result << "\n";
char response;
std::cin>>response;
return 0;
}

int Double(int original)
{
if (original <= 10000)
return original * 2;
else
return -1;
std::cout << "You can't get here!\n";
}