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Hi everyone! I am working my way through some problems from projecteuler.net and came across one that has stalled me. The task is to find the sum of all primes under 2,000,000.

I am attempting to use the Sieve of Eratosthenes algorithm for identifying prime numbers.

Here is my code so far:

```
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
namespace Euler10._1
{
class Program
{
static void Main(string[] args)
{
Program p = new Program();
p.Run();
}
public void Run()
{
int primeSum = 0;
int limit = 2000000;
List<int> primeList = SieveOfEratosthenes(limit);
foreach (int prime in primeList)
{
primeSum += prime;
}
Console.WriteLine("Sum of primes under limit ({0}) is: {1}", limit, primeSum);
}
public List<int> SieveOfEratosthenes(int limit)
{
//List<bool> primeNumbers = new List<bool>();
//primeNumbers.Add(false);
//primeNumbers.Add(false);
// create bool array to store whether value is prime or not
bool[] primeNumbers = new bool[limit];
for (int i = 2; i < limit; i++)
{
primeNumbers[i] = true;
}
// BitArray primeNumbers = new BitArray(limit, true);
primeNumbers[0] = false;
primeNumbers[1] = false;
for (long i = 2; i < limit; i++)
{
if (primeNumbers[i])
{
for (long j = i * i; j < limit; j += i)
{
primeNumbers[j] = false;
}
}
}
List<int> primeList = new List<int>();
for (int i = 2; i < limit; i++)
{
if (primeNumbers[i] == true)
{
primeList.Add(i);
}
}
return primeList;
}
}
}
```

If I use 1,000,000 for the limit, it returns "-1104303641" as the sum, which is odd because it is negative. I may be missing something obvious here, so I'm sorry in advance if that is the case.

Any thoughts?