uses crt;
var a,b,c,d,kt:integer;
begin
clrscr;
write('a='); readln(a);
write('b='); readln(b);
write('c='); readln(c);
write('d='); readln(d);
if (a>0) and (b>0) and (c>0) and (d>0) then
begin
kt:=0;
if (a=b) and (c=d) then kt:=1;
if (a=c) and (b=d) then kt:=1;
if (a=d) and (b=c) then kt:=1;
if (b=c) and (a=d) then kt:=1;
if (b=d) and (a=c) then kt:=1;
if (c=d) and (a=b) then kt:=1;
if kt=0 then writeln('day khong la 4 canh trong mot hinh binh hanh')
else writeln('day la 4 canh trong mot hinh binh hanh');
end
else writeln('vui long nhap 4 canh lon hon 0');
readln;
end.
