Solution Of Adding Multiple Trouble

ANSWER ==== 233168
#include<iostream>
using namespace std;
int main()
{
long long int old , ne , sum;
sum = 0;
for(int k=0;k<1000;k++)
{ 
    if(k%3==0 || k%5==0)
    {  
        sum = sum + k;
    }
}
cout<<sum;

return 0;
}