c++中要求输入4个数，求4个数中偶数的和？？？求教个简单算法或程序

#include "stdio.h"
void main()
{
int a,b,c,d,sum=0;
printf("输入四个数");
scanf("%d%d%d%d",&a,&b,&c,&d);
sum += (a%2==0) ? a:0;
sum += (b%2==0) ? b:0;
sum += (c%2==0) ? c:0;
sum += (d%2==0) ? d:0;

printf("h+j+k+l=%d",sum);
}

#include<iostream>
#include<string>
using namespace std;
int main()
{
int n, sum=0;
cout << "请输入四个数,回车,按CTRL+Z结束..再按两次回车得到答案" << endl;

while ( cin >> n )
{
if (n%2 == 0)
{ sum += n;}
}
cout << sum << endl;
return 0;
}

运行结果:
请输入四个数,回车,按CTRL+Z结束..再按两次回车得到答案
20 30 2 5
^Z

52
Press any key to continue

#include<iostream>
using namespace std;
int main()
{
int i,j,n,s=0;
cout<<"输入你要求的个数n:"<<endl;
cin>>n;
co