CodeForces - 1109A

#include<cstdio>
#include<map>
#include<iostream>
#include<algorithm>
using namespace std;

int n;
long long ans,pre;
map<pair<int,int>,int> M;
main()
{
    scanf("%d",&n);
    cin>>pre;
    M[{,pre}]++;
    for(int i=,x;i<=n;i++){
        scanf("%d",&x);
        pre^=x;
        ans+=M[{i&,pre}];
        if(pre==&&i%==) ans++;
        M[{i&,pre}]++;
    }
    cout<<ans<<endl;
}