Goldbach's conjecture in C (99% Finished)

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C

mathematics

Goldbach's conjecture is one of the oldest and best-known unsolved problems in number theory and in all of mathematics. It states:

Every even integer greater than 2 can be expressed as the sum of two primes.
The conjecture has been shown to hold up through 4 × 1018 and is generally assumed to be true, but remains unproven despite considerable effort.

I make the project in C to prove his conjecture but I have missed a little detail. The program prints all the possible numbers that can create an N number.

Eg for number 14 the ouput prints

3 11
7 7

where the first number called p1 and the second one is p2 in my code.
I just want to keep the number with the smallest p1 not all the numbers.

I though to store p1 and p2 to a 2d array but that's how I created the program and I don't want to start over. How can I fix it?

The code is the following:

#include<stdio.h>
#include<math.h>
int primecheck(long int x);

int main()
{
  long int a,p1,p2;
  int i,j,k;
  
  FILE *input =  fopen("goldbach.in","r");
  fscanf(input,"%ld",&a);
  fclose(input);
  
  FILE *output = fopen("goldbach.out","w+");

  if ((a%2)==1)
  {
    return 1;
  }
  
  for (p1=2;p1<a;++p1)
  {
    for (p2=2;p2<a;++p2)
    {
     j=primecheck(p1),k=primecheck(p2);
       if ((j==0) && (k==0) && (p1+p2==a) && (p1<=p2))
		fprintf(output,"%ld %ld\n",p1,p2);
        
  }
  }
 fclose(output);
}

int primecheck(long int x)
{
long int i=2;
while (i<x)
{
if ((x%i)==0)
break;
++i;
}
if (i==x)
return(0);
else
return(1);
}