pascal算24!给出4个1到1000之间的整数,用这4个整数,通过+、–、*的运算而得到24,运算规则如下：1．每个

const cha:array[1..3]of char=('+','-','*');
var a,c,d:array[1..4]of longint; b:array[1..4]of boolean;
procedure print;
var i:longint;
begin
write(c[1]);
for i:=1 to 3 do write(cha[d[i]],c[i+1]);
writeln('=24');
halt;
end;
procedure cal;
var i:longint; s:int64;
begin
s:=c[1];
for i:=1 to 3 do
case d[i] of
1:s:=s+c[i+1];
2:s:=s-c[i+1];
3:s:=s*c[i+1];
end;
if s=24 then print;
end;
procedure ch(dep:longint);
var i:longint;
begin
if dep>3
then cal
else for i:=1 to 3 do
begin
d[dep]:=i;
ch(dep+1);
end;
end;
procedure find(dep:longint);
var i:longint;
begin
if dep>4
then ch(1)
else for i:=1 to 4 do
if b[i]
then begin
b[i]:=false;
c[dep]:=a[i];
find(dep+1);
b[i]:=true;
end;
end;
begin
read(a[1],a[2],a[3],a[4]);
fillchar(b,sizeof(b),true);
find(1);
writeln('error');
end.