求教c++！！！

#include <iostream>
using namespace std;
void main()
{
int i,n,sumo = 1,sumj = 0;
cout<<"enter the value of n!" <<endl;
cin>>n;
for(i = 0;i < n; i++)
{
if(0 == i%2)
{
sumo *= i;
}
else
{
sumj += i;
}
}
cout<<""1到n之间，所有奇数和是"<<sumj<<""，所有偶数乘积是" <<sumo<<endl;
}

#include<iostream.h>
void main()
{
int n,i,a=0,b=1;
cin>>n;
for(i=1;i<=n;i++)
{if(i%2)
a+=i;
else
b*=n;
}
cout<<a<<endl<<b<<endl;

}