Codeforces Round #560 (Div. 3)

//A
#include <bits/stdc++.h>
using namespace std;
int main()
{
	int n,x,y;
	string s;
	scanf("%d %d %d",&n,&x,&y);
	cin>>s;
	int ans=0;
	for(int i=n-x;i<n;i++){
		if(s[i]=='1'&&i!=n-y-1){
				s[i] = '0';
				ans++;
		}else if(s[i]=='0'&&i==n-y-1){
			s[i]='1';ans++;
		}
	}
	//cout<<s<<" "<<ans<<endl;
	cout<<ans<<endl;
	
	return 0;
 } 

//B
#include <bits/stdc++.h>
using namespace std;
#define ll long long 
#define rep(i,x,y) for(int i=x;i<=y;i++)
#define per(i,x,y) for(int i=y;i<=x;i++)
const int N = 2e5+10;
vector<int> a;
int book[N];
int main()
{
	int n;
	scanf("%d",&n);
	rep(i,1,n){
		int t;
		scanf("%d",&t);
		a.push_back(t); 
	}
	sort(a.begin(),a.end());
	int ans = 0;
	rep(i,1,n){
		int tp = lower_bound(a.begin(),a.end(),i) - a.begin();
		if(tp==a.size()){//所有元素都小于i 
			break;
		}else {
			a.erase(a.begin()+tp);
			ans = i;
		}
	}
	printf("%d\n",ans);
	return 0;
}

//C
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define rep(i,x,y) for(int i=x;i<=y;i++)
#define per(i,x,y) for(int i=y;i<=x;i++)
const int N = 2e5+10;
char s[N];
char ts[N];
int n,cnt,ans;
int check(){
	for(int i=1;i<=n;i+=2){
		if((i&1)&&s[i]==s[i+1]){
			return 0;
		}
	}
	return 1;
}
void solve(){
	cnt = 0;
	int flag = 0;
	for(int i=1;i<=n;i++,flag^=1){
		if(s[i]==s[i+1]&&flag==0){
			ans++;
			flag^=1;//删除产生的影响 
			continue;
		}
		ts[++cnt] = s[i];
	}
	rep(i,1,cnt)s[i] = ts[i];
	
	n = cnt;
}
int main()
{
	scanf("%d",&n);
	getchar();
	rep(i,1,n){
		scanf("%c",&s[i]);
	}
	if(check()&&n%2==0){
		printf("0\n");
		printf("%s",s+1);
		return 0;
	}
	ans = 0;
	while(check()==0){
		solve();
	}
	if(n%2==1){
		ans++; n--;
	}
	printf("%d\n",ans);
	rep(i,1,n)printf("%c",s[i]);
	return 0;
}

#include <bits/stdc++.h>
using namespace std;
#define ll long long
int is[1000005];
ll a[1000005];
void getP() {
	is[0] = 1;
	is[1] = 1;
	is[2] = 0;
	for(int i=2; i<=1000005; i++) {
		if(!is[i]) {
			for(int j = i+i; j<=1000005; j+=i) {
				is[j] = 1;
			}
		}
	}
}
int judge(ll ans){
	ll num = 1;
	for(ll i = 2;i*i<=ans;i++){
		if(ans%i==0){
			ll at = 0;
			while(ans%i==0){
				ans/=i;
				at++;
			}
			num=num*(at+1);
		}
	}
	if(ans>1)num*=2;
	return num;
}
int main() {
	ll t,n,mi,mx,ans;
	getP();
	cin.tie(0);
	cin>>t;
	while(t--) {
		cin>>n;
		cin>>a[0];
		mi = a[0];
		mx = a[0];

		if(n==1) {
			if(!is[a[0]]) {
				ans=a[0]*a[0];
			} else ans = -1;
		} else {
			
			for(int i=1; i<=n-1; i++) {
				cin>>a[i];
			}
			sort(a,a+n);
			ans = a[0]*a[n-1];
			for(int i=0;i<n/2;i++){
				if(a[i]*a[n-1-i]==ans);
				else {
					ans = -1;
					break;
				}
			}
			 if(n%2==1&&a[n/2]*a[n/2]!=ans)ans = -1;
			 if(judge(ans)-2!=n)ans = -1;
		}

		cout<<ans<<endl;
	}

	return 0;
}