factorials

How I can read from standard input 3!!! or 2/3 in Pascal?

Read it as a string, then parse it :)

How I can parse string? I don't know how pascal can make integer or longint from a part of string?

Well, that is one of the clues in the problem.

When you read a string "s" with: readln(s), then you can access all the elements of "s" as s[0], s[1], ...

from these values you can reconstruct the number.

Try to google string functions in pascal, like Str, Val, Copy, Delete, Pos...

s[1],s[2] is an element of string, a part of number. But this element is also string type,so I can write this value to integer variable,so I can make a number in integer variable.

Example:
var s:string
a:integer;
begin
readln(s);
a:=s[2]; {s[2]is for example 3}

An error type mismatch occures. This is my problem whith this.

Here is part of my code, that gives you reading input.

ReadLn(Strr);
Poz:=Pos('!', Strr);
Val(Copy(Strr, 1, Poz - 1), n);
Delete(Strr, 1, Poz - 1);
k:=LengTh(Strr);

Strr is a String type. N & K are LongInt.

For your case to parse S[2] to Int type you should write this.

  Val ( Copy ( S, 2, 1 ) , A );

Look at this site.

http://www.macdonald.egate.net/CompSci/Pascal/hstrings.html

thanks a lot. Does Pascal have more functions and procedures like val,copy etc?

Don't know. Google it. :) I use Chr and Ord function for characters.