Wa in AP - Complete The Series v2

[iit2011101]

#include <iostream>
#include<cstdio>
using namespace std;
int main()
{
    int times;
scanf("%d",&times);

for ( int k = 0; k < times; k++ ) {

 long long int a3,l4,s;

scanf("%lld",&a3);
scanf("%lld",&l4);
scanf("%lld",&s);

 long long int n = 4;

double fx;

while ( fx != 0 ) {
	if ( n == 6 ) {
		n++;
	}
	fx = s - (n/2)* (a3 + l4 + ((l4 - a3)/(double)(n-6)) );
	n++;
}
n = n-1;
printf("%ulld\n",n);
 double  d = (l4-a3)/(double)(n-6);
 long long int a = a3 - (2*d);

for ( int i = 0; i < n ; i++ ) {
 	long long int k = a+i*d;
	printf("%ulld",k);
	printf("  ");
}
printf("\n");
}
return 0;
}