Ошибка в коде

#include <iostream>
using namespace std;

int main()
{
int lengthOfYard;
int widthOfYard;
int areaOfYard;

cout << "\n How wide is your yard? ";
cin >> widthOfYard;
cout << "\n How long is your yard? ";
cin >> lengthOfYard;

areaOfYard = Area (lengthOfYard, widthOfYard);

cout << "\n Your yard is ";
cout << areaOfYard;
cout << "square feet \n \n";
return 0;
}

int Area (int yardLength, int yardWidth)
{
return yardLength + yardWidth;
}
Area - необъявлен идентификатор