蒟蒻求助

#include <bits/stdc++.h>

using namespace std;

struct node{
	int val;
	bool flag;	
};
map<int,int> mp;

int main()
{
    int n,cnt=0;
    scanf("%d",&n);
    node a[1+n];
    for (int i=1;i<=n;i++) 
    {
        scanf("%d",&a[i].val);
        int x=a[i].val;
        mp[x]++;
        a[i].flag=0;
        if(mp[a[i].val]==3)
        {
            printf("-1\n");
            return 0;
        }
    }
    for (int i=1;i<=n;i++)
    {
        if(mp[a[i].val]==2&&a[i].flag==0) 
		{
			cnt++;
			a[i].flag=1;
			cout<<"a[i]:"<<a[i].val<<' '<<mp[a[i].val]<<endl;
    	}
	}
    printf("cnt:%d\n",cnt);
    return 0;
}