c++ sum of 2 prime numbers

hey...
im tryin to write a code that when input a number n it outputs p and q where p and q are both prime numbers and fits the equation n = p + q...(q = n - p)
in ths code im not allowed to use the mod sign (%)..
please help...

thanks

[pred]Sounds like you want us to do your homework. At least try something, and then post the code here, so we can tell you what you're doing wrong.[/pred]

this is the code i have so far.. how can i change it so i dnt use the mod % sign??

#include <iostream>
using namespace std;

int goldback(int n, int p, int q);

int main()
{
int N;
int P = 3;
int Q = 3;

while (N != -1){
cin >> N;
goldback(N, P, Q);
}

return 0;
}

int goldback(int n, int p, int q)
{
int pprime = 0;
int qprime = 0;
for (int i = p; i < n; i++)
{
for (int j = 2; j < i; j++)
if (i%j == 0)
pprime++;
if (pprime == 0)
for (int k = q; k < n; k++)
{
for (int m = 2; m < k; m++)
if (k%m == 0)
qprime++;
if (qprime == 0)
if (n == (i + k))
{
cout << "prime numbers " << i << " and " << k << endl;
return 0;
}
qprime = 0;
}
pprime = 0;
}
return 1;
}

this there any other way to do this???

Easy way? Replace it with:

Make sure not to use any optimizers though, they might kick this out...