这里是代码

#include <iostream>
using namespace std;
int main()
{
    int a,Count=0;
    cin>>a;
    int b[a];
    bool c[10000];
    for (int i0=0;i0<a;i0++)
    {
        cin>>b[i0];
        c[b[i0]]=1;
    }
    for (int i1=0;i1<a-1;i1++)
    {
        for (int i2=i1+1;i2<a;i2++)
        {
            if (c[b[i1]+b[i2]]==1)
            {
                Count++;
                c[b[i1]+b[i2]]=0;
            }
        }
    }
    cout<<Count;
    return 0;
}