program MinNumber;
function Min$a,b,c,d:Integer$: Integer;
begin
Result := a;
if b < Result then
Result := b;
if c < Result then
Result := c;
if d < Result then
Result := d;
end;
var
a, b, c, d, minNum: Integer;
begin
writeln${}^{\prime }Enterfournumbers{:}^{\prime }$;
readln$a,b,c,d$;
minNum := Min$a,b,c,d$;
writeln${}^{\prime }Theminimumnumberis{:}^{\prime },minNum$;
end.

Пример использования:

Enter four numbers:
5
7
3
9
The minimum number is: 3