var ans:qword;
a,b:int64;
ans1:string;
i,n:integer;
begin
readln(a,b);
ans:=a-b;
str(ans,ans1);
n:=length(ans1);
if a-b>0 then
begin
for i:=1 to n do
begin
write(ans1[i]);
if ((n-i) mod 3=0) and (i<>n) then write(',');
end;
end
else
begin
write('-');
for i:=1 to n do
begin
write(ans1[i]);
if ((n-i) mod 3=0) and (i<>n) then write(',');
end;
end;
end.
为啥20分？