UVa 686 - Goldbach's Conjecture (II) solution

Problem link :  UVa 686 - Goldbach's Conjecture (II)

Solution : 


#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<math.h>
using namespace std;

bool Isp(int n)
{
    int i,j;
    if(n==1)
    return 0;

    if(n==2)
    return 1;

    if(n%2==0)
    return 0;

    int l=sqrt(n);

    for(i=3;i<=l;i+=2)
    {
        if(n%i==0)
        return 0;
    }
    return 1;
}
int main()
{
    int a,b,i,m,n,c;
    while(scanf("%d",&n)==1)
    {
        if(n==0)
        break;

        a=0,b=0,c=0;

        for(i=n-1;i>=n/2;i--)
        {
            if(Isp(i))
            {
                m=n-i;
                if(Isp(m))
                {
                    c++;
                }
            }
        }

        printf("%d\n",c);
    }
    return 0;
}