Developing.ru

var k,a,b,c: longint ;
begin
k:=0;
readln (a,b,c);
if (a mod c)= 0 then
begin
while a<=b do
begin
a:=a+c;
k:=k+1;
end;
end
else
begin
while ((a<b) and (a mod c<>0)) do
begin
a:=a+1;
and;
while a<=b do
begin
a:=a+c;
k:=k+1;
end;
end;
writeln (k);
end.