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#define ll long long #define pb push_back #define ipar(arr, n) vector<ll> arr(n); for(int i=0;i<n;i++) cin>>arr[i]; #include <cmath> using namespace std; void solve(){ ll n,k;cin>>n>>k; ipar(arr,n); ll ec=0; for(int i=0;i<n;i++){ if(arr[i]%2==0) ec++; } if(k%2==1){ cout<<ceil((double)ec/2)<<"\n"; return; } if(k%2==0 && ec==n){ cout<<-1<<"\n"; return; } if(k%2==0 && ec<n){ cout<<ec<<"\n"; return; } } signed main() { ios_base::sync_with_stdio(0); cin.tie(0);cout.tie(0); int t; cin>>t; while(t--) solve(); }
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