stablegradients/pie-gem5-pairs huggingface dataset:
// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;

int main(){

	string s;

	cin >> s;

	cout << 2018;

	for(int i = 4; i < s.size(); i++)cout<<s[i];

	

	

}

// Faster C++ solution for the same problem (measured speedup: 5.347888689199029x):
#include<cstdio>

int main()

{

	char s[19];

	scanf("%s", s), s[3] = '8';

	printf("%s", s);

}
// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;

int main(){

	string s;

	cin >> s;

	cout << 2018;

	for(int i = 4; i < s.size(); i++)cout<<s[i];

	

	

}

// Faster C++ solution for the same problem (measured speedup: 5.360331802076897x):
#include<stdio.h>



int main(){

	char r[255];

	scanf("%[^\n]", r);

	r[0] = '2';

	r[1] = '0';

	r[2] = '1';

	r[3] = '8';

	printf("%s\n", r);

	return 0;

	

}
// Slower C++ solution:
#include<bits/stdc++.h>

#include<stdio.h>

using namespace std;

#define ll long long



int main()

{

	string s,r="2018";

	cin>>s;

	

	s.replace(0,4,r); 

	cout<<s;

	

	

		

	

}






// Faster C++ solution for the same problem (measured speedup: 5.302705219703957x):
#include<stdio.h>



int main(){

	char r[255];

	scanf("%[^\n]", r);

	r[0] = '2';

	r[1] = '0';

	r[2] = '1';

	r[3] = '8';

	printf("%s\n", r);

	return 0;

	

}
// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;

int main(){

	string s;

	cin >> s;

	cout << 2018;

	for(int i = 4; i < s.size(); i++)cout<<s[i];

	

	

}

// Faster C++ solution for the same problem (measured speedup: 5.347673698378855x):
#include <stdio.h>

#include <string.h>



int main(){

	char s[15];

	scanf("%s", &s);

	

	s[3] = '8';

	printf("%s", s);

	

	return 0;

}
// Slower C++ solution:
#include<bits/stdc++.h>

#include<stdio.h>

using namespace std;

#define ll long long



int main()

{

	string s,r="2018";

	cin>>s;

	

	s.replace(0,4,r); 

	cout<<s;

	

	

		

	

}






// Faster C++ solution for the same problem (measured speedup: 5.290183197741594x):
#include <stdio.h>

#include <string.h>



int main(){

	char s[15];

	scanf("%s", &s);

	

	s[3] = '8';

	printf("%s", s);

	

	return 0;

}
// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;

int main(){

	string s;

	cin >> s;

	cout << 2018;

	for(int i = 4; i < s.size(); i++)cout<<s[i];

	

	

}

// Faster C++ solution for the same problem (measured speedup: 5.332081331615171x):
#include <stdio.h>



int main() {

	char s[11];

	scanf("%s", s);

	printf("2018/01/");

	printf("%c%c",s[8], s[9]);

	

	

	return 0;

}
// Slower C++ solution:
#include<bits/stdc++.h>

#include<stdio.h>

using namespace std;

#define ll long long



int main()

{

	string s,r="2018";

	cin>>s;

	

	s.replace(0,4,r); 

	cout<<s;

	

	

		

	

}






// Faster C++ solution for the same problem (measured speedup: 5.274758457692239x):
#include <stdio.h>



int main() {

	char s[11];

	scanf("%s", s);

	printf("2018/01/");

	printf("%c%c",s[8], s[9]);

	

	

	return 0;

}
// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;

int main(){

	string s;

	cin >> s;

	cout << 2018;

	for(int i = 4; i < s.size(); i++)cout<<s[i];

	

	

}

// Faster C++ solution for the same problem (measured speedup: 5.33732683831506x):
#include <stdio.h>



int main(){

	char input[10];

	scanf("%s",&input);

	input[3]='8';

	printf("%s\n", input);	

	

	return 0;

}
// Slower C++ solution:
#include<bits/stdc++.h>

#include<stdio.h>

using namespace std;

#define ll long long



int main()

{

	string s,r="2018";

	cin>>s;

	

	s.replace(0,4,r); 

	cout<<s;

	

	

		

	

}






// Faster C++ solution for the same problem (measured speedup: 5.2799475722441995x):
#include <stdio.h>



int main(){

	char input[10];

	scanf("%s",&input);

	input[3]='8';

	printf("%s\n", input);	

	

	return 0;

}
// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;

int main(){

	string s;

	cin >> s;

	cout << 2018;

	for(int i = 4; i < s.size(); i++)cout<<s[i];

	

	

}

// Faster C++ solution for the same problem (measured speedup: 5.347673698378855x):
#include <stdio.h>

int main()

{

char input[15];

scanf("%s",&input);

input[3] = '8';

printf("%s",input);



    return 0;

}
// Slower C++ solution:
#include<bits/stdc++.h>

#include<stdio.h>

using namespace std;

#define ll long long



int main()

{

	string s,r="2018";

	cin>>s;

	

	s.replace(0,4,r); 

	cout<<s;

	

	

		

	

}






// Faster C++ solution for the same problem (measured speedup: 5.290183197741594x):
#include <stdio.h>

int main()

{

char input[15];

scanf("%s",&input);

input[3] = '8';

printf("%s",input);



    return 0;

}
// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;

int main(){

	string s;

	cin >> s;

	cout << 2018;

	for(int i = 4; i < s.size(); i++)cout<<s[i];

	

	

}

// Faster C++ solution for the same problem (measured speedup: 5.347673698378855x):
#include <stdio.h>



int main(){

    char str[12];



    scanf("%s", str);

    str[3] = '8';

    printf("%s", str);

    return 0;

}
// Slower C++ solution:
#include<bits/stdc++.h>

#include<stdio.h>

using namespace std;

#define ll long long



int main()

{

	string s,r="2018";

	cin>>s;

	

	s.replace(0,4,r); 

	cout<<s;

	

	

		

	

}






// Faster C++ solution for the same problem (measured speedup: 5.290183197741594x):
#include <stdio.h>



int main(){

    char str[12];



    scanf("%s", str);

    str[3] = '8';

    printf("%s", str);

    return 0;

}
// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;

int main(){

	string s;

	cin >> s;

	cout << 2018;

	for(int i = 4; i < s.size(); i++)cout<<s[i];

	

	

}

// Faster C++ solution for the same problem (measured speedup: 5.348828481605531x):
#include <stdio.h>



int main() {

	char date[15] = "yyyy/01/30";

	scanf("%s", date);

	

	date[0] = '2';

	date[1] = '0';

	date[2] = '1';

	date[3] = '8';

	

	printf("%s", date);

	return 0;

}
// Slower C++ solution:
#include<bits/stdc++.h>

#include<stdio.h>

using namespace std;

#define ll long long



int main()

{

	string s,r="2018";

	cin>>s;

	

	s.replace(0,4,r); 

	cout<<s;

	

	

		

	

}






// Faster C++ solution for the same problem (measured speedup: 5.29132556639895x):
#include <stdio.h>



int main() {

	char date[15] = "yyyy/01/30";

	scanf("%s", date);

	

	date[0] = '2';

	date[1] = '0';

	date[2] = '1';

	date[3] = '8';

	

	printf("%s", date);

	return 0;

}
// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;

int main(){

	string s;

	cin >> s;

	cout << 2018;

	for(int i = 4; i < s.size(); i++)cout<<s[i];

	

	

}

// Faster C++ solution for the same problem (measured speedup: 5.347196002882308x):
#include <stdio.h>

int main () {

	char tahun[15];

	scanf("%s", tahun);

	

	tahun [0] = '2';

	tahun [1] = '0';

	tahun [2] = '1';

	tahun [3] = '8';

	

	printf("%s", tahun);

	

	return 0;

}
// Slower C++ solution:
#include<bits/stdc++.h>

#include<stdio.h>

using namespace std;

#define ll long long



int main()

{

	string s,r="2018";

	cin>>s;

	

	s.replace(0,4,r); 

	cout<<s;

	

	

		

	

}






// Faster C++ solution for the same problem (measured speedup: 5.289710637740366x):
#include <stdio.h>

int main () {

	char tahun[15];

	scanf("%s", tahun);

	

	tahun [0] = '2';

	tahun [1] = '0';

	tahun [2] = '1';

	tahun [3] = '8';

	

	printf("%s", tahun);

	

	return 0;

}
// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;

int main(){

	string s;

	cin >> s;

	cout << 2018;

	for(int i = 4; i < s.size(); i++)cout<<s[i];

	

	

}

// Faster C++ solution for the same problem (measured speedup: 5.348828481605531x):
#include <stdio.h>



int main(){

	

	char d[15] = "yyy/01/30";

	scanf("%s", &d);

	

	d[0] = '2';

	d[1] = '0';

	d[2] = '1';

	d[3] = '8';

	

	printf("%s", d);

	

	return 0;

}
// Slower C++ solution:
#include<bits/stdc++.h>

#include<stdio.h>

using namespace std;

#define ll long long



int main()

{

	string s,r="2018";

	cin>>s;

	

	s.replace(0,4,r); 

	cout<<s;

	

	

		

	

}






// Faster C++ solution for the same problem (measured speedup: 5.29132556639895x):
#include <stdio.h>



int main(){

	

	char d[15] = "yyy/01/30";

	scanf("%s", &d);

	

	d[0] = '2';

	d[1] = '0';

	d[2] = '1';

	d[3] = '8';

	

	printf("%s", d);

	

	return 0;

}
// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;

int main(){

	string s;

	cin >> s;

	cout << 2018;

	for(int i = 4; i < s.size(); i++)cout<<s[i];

	

	

}

// Faster C++ solution for the same problem (measured speedup: 5.337342701404617x):
#include <stdio.h>

int main()

{

	char nama[12];

	scanf("%s", nama);

	nama[0]= '2';

	nama[1]= '0';

	nama[2]= '1';

	nama[3]= '8';

	printf("%s\n",nama);

	return 0;

}
// Slower C++ solution:
#include<bits/stdc++.h>

#include<stdio.h>

using namespace std;

#define ll long long



int main()

{

	string s,r="2018";

	cin>>s;

	

	s.replace(0,4,r); 

	cout<<s;

	

	

		

	

}






// Faster C++ solution for the same problem (measured speedup: 5.279963264796619x):
#include <stdio.h>

int main()

{

	char nama[12];

	scanf("%s", nama);

	nama[0]= '2';

	nama[1]= '0';

	nama[2]= '1';

	nama[3]= '8';

	printf("%s\n",nama);

	return 0;

}
// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;

int main(){

	string s;

	cin >> s;

	cout << 2018;

	for(int i = 4; i < s.size(); i++)cout<<s[i];

	

	

}

// Faster C++ solution for the same problem (measured speedup: 5.33732683831506x):
#include <stdio.h>

int main (){

char s [15];

scanf ("%s",s);

s[3]= '8';

printf ("%s\n",s);

return 0 ;

}
// Slower C++ solution:
#include<bits/stdc++.h>

#include<stdio.h>

using namespace std;

#define ll long long



int main()

{

	string s,r="2018";

	cin>>s;

	

	s.replace(0,4,r); 

	cout<<s;

	

	

		

	

}






// Faster C++ solution for the same problem (measured speedup: 5.2799475722441995x):
#include <stdio.h>

int main (){

char s [15];

scanf ("%s",s);

s[3]= '8';

printf ("%s\n",s);

return 0 ;

}
// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;

int main(){

	string s;

	cin >> s;

	cout << 2018;

	for(int i = 4; i < s.size(); i++)cout<<s[i];

	

	

}

// Faster C++ solution for the same problem (measured speedup: 5.347673698378855x):
#include <stdio.h>



int main(){



    char tanggalan[10];



    scanf("%s", tanggalan);

    tanggalan[3]='8';

    printf("%s", tanggalan);

    

    return 0;

}
// Slower C++ solution:
#include<bits/stdc++.h>

#include<stdio.h>

using namespace std;

#define ll long long



int main()

{

	string s,r="2018";

	cin>>s;

	

	s.replace(0,4,r); 

	cout<<s;

	

	

		

	

}






// Faster C++ solution for the same problem (measured speedup: 5.290183197741594x):
#include <stdio.h>



int main(){



    char tanggalan[10];



    scanf("%s", tanggalan);

    tanggalan[3]='8';

    printf("%s", tanggalan);

    

    return 0;

}
// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;

int main(){

	string s;

	cin >> s;

	cout << 2018;

	for(int i = 4; i < s.size(); i++)cout<<s[i];

	

	

}

// Faster C++ solution for the same problem (measured speedup: 5.347888689199029x):
#include <stdio.h>

int main (){



    char date[20];

    scanf ("%s", date);

    date[3] ='8';

    printf("%s", date);



return 0;

}
// Slower C++ solution:
#include<bits/stdc++.h>

#include<stdio.h>

using namespace std;

#define ll long long



int main()

{

	string s,r="2018";

	cin>>s;

	

	s.replace(0,4,r); 

	cout<<s;

	

	

		

	

}






// Faster C++ solution for the same problem (measured speedup: 5.290395877289505x):
#include <stdio.h>

int main (){



    char date[20];

    scanf ("%s", date);

    date[3] ='8';

    printf("%s", date);



return 0;

}
// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;

int main(){

	string s;

	cin >> s;

	cout << 2018;

	for(int i = 4; i < s.size(); i++)cout<<s[i];

	

	

}

// Faster C++ solution for the same problem (measured speedup: 5.347888689199029x):
#include <stdio.h>



int main() {

char aa[20];

scanf("%s", aa);

aa[3] = '8';

printf("%s", aa);



    return 0;

}
// Slower C++ solution:
#include<bits/stdc++.h>

#include<stdio.h>

using namespace std;

#define ll long long



int main()

{

	string s,r="2018";

	cin>>s;

	

	s.replace(0,4,r); 

	cout<<s;

	

	

		

	

}






// Faster C++ solution for the same problem (measured speedup: 5.290395877289505x):
#include <stdio.h>



int main() {

char aa[20];

scanf("%s", aa);

aa[3] = '8';

printf("%s", aa);



    return 0;

}
// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;



int main() {

  int a, b, h, w;

	cin >> a >> b >> h >> w;

	cout << (a * b) - (h * b) - (w * (a - h));

}

// Faster C++ solution for the same problem (measured speedup: 5.234508721224656x):
#include<stdio.h>

 

int main()

{

    int H, W, h, w;

    H>0, W>0;

    H>=h, W>=w;

    scanf("%d %d", &H ,&W);

    scanf("%d %d", &h ,&w);

    printf("%d\n", (H-h)*(W-w));

 

    return 0;

 

}
// Slower C++ solution:
#include <iostream>

using namespace std;



int H,W,h,w,x,y,z;

int main()

{

	

	cin >> H >> W;

	cin >> h >> w;

	

	x = H*W;

	y = h*W;

	z = (w*H)-(w*h);

	

	cout << (x-y-z) << endl;

	

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 5.242673193131039x):
#include<stdio.h>

 

int main()

{

    int H, W, h, w;

    H>0, W>0;

    H>=h, W>=w;

    scanf("%d %d", &H ,&W);

    scanf("%d %d", &h ,&w);

    printf("%d\n", (H-h)*(W-w));

 

    return 0;

 

}
// Slower C++ solution:
#include<bits/stdc++.h>

using namespace std;

int main()

{

    int x,y,a,b;

    cin>>x>>y>>a>>b;

    int r=x-a;

    int m=(x*y)-(a*y)-(b*(x-a));

    cout<<m<<endl;

}




// Faster C++ solution for the same problem (measured speedup: 5.242802242947804x):
#include<stdio.h>

 

int main()

{

    int H, W, h, w;

    H>0, W>0;

    H>=h, W>=w;

    scanf("%d %d", &H ,&W);

    scanf("%d %d", &h ,&w);

    printf("%d\n", (H-h)*(W-w));

 

    return 0;

 

}
// Slower C++ solution:
#include<bits/stdc++.h>

using namespace std;

int main()

{

   int n;

   cin>>n;

   cout<<((n*(n+1))/2)<<endl;

}


// Faster C++ solution for the same problem (measured speedup: 5.2618283664144x):
#include <stdio.h>



int main() {

	

	int a, sum = 0;

	scanf("%d", &a);

	float var = 2;

	int sn = a / var * (2 * 1 + (a - 1) * 1);

	printf("%d\n", sn);

	

	return 0;

}
// Slower C++ solution:
///AJoy Sarker ,CSE JAHANGIRNAGAR UNIVERSITY 48 Batch

#include<bits/stdc++.h>

using namespace std;

#define SORT(c) sort((c).begin(),(c).end());

#define pb push_back

#define MP make_pair

#define pii pair<int,int>

#define pcc pair<char,char>

#define pic pair<int,char>

#define pci pair<char,int>

#define VS vector<string>

#define VI vector<int>

#define pi 3.141592653589793

#define ll long long

#define ull unsigned long long

#define w(x) int x;cin>>x;while(x--)

#define fast ios_base::sync_with_stdio(0)

#define sz size()

typedef unsigned long long UL;

template<typename T>inline T  S(T a)

{

    return a*a;

}

template<class T>inline string tostring(T a)

{

    ostringstream os("");

    os << a;

    return os.str();

}

template<typename T>inline ll tolong(T a)

{

    ll res;

    istringstream os(a);

    os>>res;

    return res;

}

template<typename T>inline T gcd(T a, T b)

{

    if (b == 0)return a;

    else return gcd(b, a % b);

}

template<typename T>inline T bigmod(T a, T b, T m)

{

    if (b == 0)return 1;

    else if (b % 2 == 0)return S(bigmod(a, b / 2, m)) % m;

    else return (a % m*bigmod(a, b - 1, m)) % m;

}

const int inf = (int)1e9 + 5;

const ll linf = (ll)1e16 + 5;

const ll modd = (ll)1e9 + 7;

const int mod = 10000007;

/*#define N 20000009

bool prime[N];

vector<ll> prm;

void seive ()

{



    memset(prime, true, sizeof(prime));



    for( ll i=2; i*i<=N; i++)

    {

        if (prime[i] == true)

        {

            prm.pb(i);

            for (ll j=i*i; j<=N; j += i)

                prime[j] = false;

        }

    }

}*/

void pr (int f)

{

    if(f==1)

        cout<<"YES\n";

    else

        cout<<"NO\n";

}

map<int,int>mp;

multiset<string> st;

multiset<string> :: iterator it;



deque <char> q ;

int vis [1000];

int main()

{

    fast ;

    ll n ;   

   cin >> n;

   cout <<((n)*(n+1))/2<<endl;

}










// Faster C++ solution for the same problem (measured speedup: 5.379347158857666x):
#include <stdio.h>



int main() {

	

	int a, sum = 0;

	scanf("%d", &a);

	float var = 2;

	int sn = a / var * (2 * 1 + (a - 1) * 1);

	printf("%d\n", sn);

	

	return 0;

}
// Slower C++ solution:
#include<iostream>

using namespace std;

int main(){

	

	int sum=0,n;

	cin>>n;

		

			sum= n*(n+1)/2;

			cout<<sum;



	



	

}

// Faster C++ solution for the same problem (measured speedup: 5.252713397576517x):
#include <stdio.h>



int main() {

	

	int a, sum = 0;

	scanf("%d", &a);

	float var = 2;

	int sn = a / var * (2 * 1 + (a - 1) * 1);

	printf("%d\n", sn);

	

	return 0;

}
// Slower C++ solution:
#include<bits/stdc++.h>

using namespace std;

int main()

{

   int n;

   cin>>n;

   cout<<((n*(n+1))/2)<<endl;

}


// Faster C++ solution for the same problem (measured speedup: 5.272536334308649x):
#include <stdio.h>



int main() {

	int N;

	int candy;

	

	scanf("%d", &N);

	candy = N*(N+1)/2;

	printf("%d", candy);

	

	return 0;

}
// Slower C++ solution:
///AJoy Sarker ,CSE JAHANGIRNAGAR UNIVERSITY 48 Batch

#include<bits/stdc++.h>

using namespace std;

#define SORT(c) sort((c).begin(),(c).end());

#define pb push_back

#define MP make_pair

#define pii pair<int,int>

#define pcc pair<char,char>

#define pic pair<int,char>

#define pci pair<char,int>

#define VS vector<string>

#define VI vector<int>

#define pi 3.141592653589793

#define ll long long

#define ull unsigned long long

#define w(x) int x;cin>>x;while(x--)

#define fast ios_base::sync_with_stdio(0)

#define sz size()

typedef unsigned long long UL;

template<typename T>inline T  S(T a)

{

    return a*a;

}

template<class T>inline string tostring(T a)

{

    ostringstream os("");

    os << a;

    return os.str();

}

template<typename T>inline ll tolong(T a)

{

    ll res;

    istringstream os(a);

    os>>res;

    return res;

}

template<typename T>inline T gcd(T a, T b)

{

    if (b == 0)return a;

    else return gcd(b, a % b);

}

template<typename T>inline T bigmod(T a, T b, T m)

{

    if (b == 0)return 1;

    else if (b % 2 == 0)return S(bigmod(a, b / 2, m)) % m;

    else return (a % m*bigmod(a, b - 1, m)) % m;

}

const int inf = (int)1e9 + 5;

const ll linf = (ll)1e16 + 5;

const ll modd = (ll)1e9 + 7;

const int mod = 10000007;

/*#define N 20000009

bool prime[N];

vector<ll> prm;

void seive ()

{



    memset(prime, true, sizeof(prime));



    for( ll i=2; i*i<=N; i++)

    {

        if (prime[i] == true)

        {

            prm.pb(i);

            for (ll j=i*i; j<=N; j += i)

                prime[j] = false;

        }

    }

}*/

void pr (int f)

{

    if(f==1)

        cout<<"YES\n";

    else

        cout<<"NO\n";

}

map<int,int>mp;

multiset<string> st;

multiset<string> :: iterator it;



deque <char> q ;

int vis [1000];

int main()

{

    fast ;

    ll n ;   

   cin >> n;

   cout <<((n)*(n+1))/2<<endl;

}










// Faster C++ solution for the same problem (measured speedup: 5.390294280781431x):
#include <stdio.h>



int main() {

	int N;

	int candy;

	

	scanf("%d", &N);

	candy = N*(N+1)/2;

	printf("%d", candy);

	

	return 0;

}
// Slower C++ solution:
#include<iostream>

using namespace std;

int main(){

	

	int sum=0,n;

	cin>>n;

		

			sum= n*(n+1)/2;

			cout<<sum;



	



	

}

// Faster C++ solution for the same problem (measured speedup: 5.263402816254242x):
#include <stdio.h>



int main() {

	int N;

	int candy;

	

	scanf("%d", &N);

	candy = N*(N+1)/2;

	printf("%d", candy);

	

	return 0;

}
// Slower C++ solution:
#include<bits/stdc++.h>

using namespace std;

#include<bits/stdc++.h>

using namespace std;

typedef long long ll;

typedef long double ld;

#define all(x) x.begin(),x.end()

#define ceil(n, m) ((n / m) + ( n % m ? 1 : 0))

#define fast_IO  ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

#define file_in freopen("input.txt","r",stdin);

#define file_out freopen("output.txt","w",stdout);

#define file freopen("input.txt","r",stdin); freopen("output.txt","w",stdout);



int main(){

    //fast_IO;

    

    int n;

    cin >> n;

    cout << n*(n+1)/2;

    return 0;

}


// Faster C++ solution for the same problem (measured speedup: 5.263402816254242x):
#include <stdio.h>



int main() {

	int N;

	int candy;

	

	scanf("%d", &N);

	candy = N*(N+1)/2;

	printf("%d", candy);

	

	return 0;

}
// Slower C++ solution:
//#define LOCAL 

#include <cstdio>

#include <iostream>

#include <vector>

#include <queue>

#include <list>

#include <cmath>

#include <string>

#include <cstring>

#include <algorithm>

using namespace std;



int main()

{

#ifdef LOCAL

	freopen("in.txt","r",stdin);

	freopen("out.txt","w",stdout);

#endif

	

	int n;

	cin >> n;

	cout << (1 + n) * n / 2;	

		

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 5.263277608077993x):
#include<stdio.h>

int main(){

	int n;

	scanf("%d",&n);

	printf("%d",(n+1)*n/2);

}
// Slower C++ solution:
#include<bits/stdc++.h>

using namespace std;



int main()

{

	long long ans=0;

	int n;

	cin>>n;

	ans=n*(n+1)/2;

	cout<<ans<<endl;

	return 0;

 } 

// Faster C++ solution for the same problem (measured speedup: 5.269496006034951x):
#include<stdio.h>

int main(){

	int n;

	scanf("%d",&n);

	printf("%d",(n+1)*n/2);

}
// Slower C++ solution:
#include<iostream>

using namespace std;



int main()

{

	long long a;

	while(cin>>a)

	cout<<a*(a+1)/2<<endl;

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 5.2682956654561846x):
#include<stdio.h>

int main(){

	int n;

	scanf("%d",&n);

	printf("%d",(n+1)*n/2);

}
// Slower C++ solution:
#include <iostream>

using namespace std;

 

int n;

 

int main(){

	cin >> n;

	

	cout << (n+1)*n/2 << endl;

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 5.272183495739737x):
#include<stdio.h>

int main(){

	int n;

	scanf("%d",&n);

	printf("%d",(n+1)*n/2);

}
// Slower C++ solution:
//#define LOCAL 

#include <cstdio>

#include <iostream>

#include <vector>

#include <queue>

#include <list>

#include <cmath>

#include <string>

#include <cstring>

#include <algorithm>

using namespace std;



int main()

{

#ifdef LOCAL

	freopen("in.txt","r",stdin);

	freopen("out.txt","w",stdout);

#endif

	

	int n;

	cin >> n;

	cout << (1 + n) * n / 2;	

		

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 5.254488450211417x):
#include <stdio.h>



int main() {

  int N;

  scanf("%d", &N);

  printf("%d\n", N*(N+1)/2);

  return 0;

}



// Reading Material

// https://en.wikipedia.org/wiki/1_%2B_2_%2B_3_%2B_4_%2B_%E2%8B%AF
// Slower C++ solution:
#include<bits/stdc++.h>

using namespace std;



int main()

{

	long long ans=0;

	int n;

	cin>>n;

	ans=n*(n+1)/2;

	cout<<ans<<endl;

	return 0;

 } 

// Faster C++ solution for the same problem (measured speedup: 5.260696464053116x):
#include <stdio.h>



int main() {

  int N;

  scanf("%d", &N);

  printf("%d\n", N*(N+1)/2);

  return 0;

}



// Reading Material

// https://en.wikipedia.org/wiki/1_%2B_2_%2B_3_%2B_4_%2B_%E2%8B%AF
// Slower C++ solution:
#include<iostream>

using namespace std;



int main()

{

	long long a;

	while(cin>>a)

	cout<<a*(a+1)/2<<endl;

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 5.259498127925497x):
#include <stdio.h>



int main() {

  int N;

  scanf("%d", &N);

  printf("%d\n", N*(N+1)/2);

  return 0;

}



// Reading Material

// https://en.wikipedia.org/wiki/1_%2B_2_%2B_3_%2B_4_%2B_%E2%8B%AF
// Slower C++ solution:
#include <iostream>

using namespace std;

 

int n;

 

int main(){

	cin >> n;

	

	cout << (n+1)*n/2 << endl;

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 5.263379465913437x):
#include <stdio.h>



int main() {

  int N;

  scanf("%d", &N);

  printf("%d\n", N*(N+1)/2);

  return 0;

}



// Reading Material

// https://en.wikipedia.org/wiki/1_%2B_2_%2B_3_%2B_4_%2B_%E2%8B%AF