This is my program. But it faces a time-out since the range extends to 10^12. My program's complexity is O(n^2). Any tips?

int main() {

long int k,n,i,f,count=0,temp;
int max;
scanf("%ld",&i);
k=1;
        f=(4*k)+4;
for(n=0;n<=i;n++)
        {

        if(n==0)
        f=f+(8*n);
        else
        f=f+8;
        temp=temp+f;
        if(temp<=i)
        max=n;
        else
        break;
}
for(k=1;k<i;k++)
    {
    f=(4*k)+4;
    temp=0;
    for(n=0;n<=max;n++)
        {
        if(n==0)
        f=f+(8*n);
        else
        f=f+8;
        temp=temp+f;
        if(temp<=i)
            {

            count++;
        }
    }
}
printf("%ld",count);

}