program TimSoLonNhat;

var

     a, b, c, d, max: integer;

begin

     write('Nhap a: '); readln(a);

     write('Nhap b: '); readln(b);

     write('Nhap c: '); readln(c);

     write('Nhap d: '); readln(d);

     max := a;

     if b > max then

          max := b;

     if c > max then

          max := c;

     if d > max then

          max := d;

     writeln('So lon nhat la: ', max);

     readln;

end.

program TimSoLonNhat;

var a, b, c, d: integer; 

begin
  writeln('Nhap vao gia tri cua a: ');
  readln(a);
  writeln('Nhap vao gia tri cua b: ');
  readln(b);
  writeln('Nhap vao gia tri cua c: ');
  readln(c);
  writeln('Nhap vao gia tri cua d: ');
  readln(d);

  if (a > b) and (a > c) and (a > d) then
    writeln('So lon nhat la: ', a)
  else if (b > a) and (b > c) and (b > d) then
    writeln('So lon nhat la: ', b)
  else if (c > a) and (c > b) and (c > d) then
    writeln('So lon nhat la: ', c)
  else
    writeln('So lon nhat la: ', d);
    readln;
end.

uses crt;

var n,i,t:integer;

begin

clrscr;

readln(n);

t:=0;

for i:=1 to n do 

  if i mod 2=1 then t:=t+i;

writeln(t);

readln;

end.

#include <bits/stdc++.h>

using namespace std;

long long n,i,t;

int main()

{

cin>>n;

t=0;

for (i=1; i<=n; i++)

if (i%2==0) t+=i;

cout<<t;

return 0;

}

#include <bits/stdc++.h>

using namespace std;

long long n,i,t;

int main()

{

cin>>n;

t=0;

for (i=1; i<=n; i++)

if (i%2!=0) t+=i;

cout<<t;

return 0;

}

program;

uses crt;

var a:longint;

begin

clrscr;

write('nhap a:');readln(a);

if(a>=0)and(a<=50)then write('n nam trong khoang tu 1 den 50')

else write('n khong nam trong khoang tu 1 den 50');

readln;

#include <bits/stdc++.h>

using namespace std;

int a;

int main()

{

cin>>a;

if ((a>=1) and (a<=50)) cout<<"YES";

else cout<<"NO";

return 0;

}