<?pas
// BigInteger: Arbitrary precision integers

// Basic operations - initialized from strings for large values
var a := BigInteger('12345678901234567890');
var b := BigInteger('98765432109876543210');

PrintLn('a = ' + a.ToString);
PrintLn('b = ' + b.ToString);
PrintLn('a + b = ' + (a + b).ToString);
PrintLn('a * b = ' + (a * b).ToString);
PrintLn('');

// Large factorial
function Factorial(n: Integer): BigInteger;
begin
  Result := BigInteger(1);
  for var i := 2 to n do
    Result := Result * i;
end;

PrintLn('50! = ');
var fact50 := Factorial(50);
PrintLn(fact50.ToString);
PrintLn('Digits: ' + fact50.ToString.Length.ToString);
PrintLn('');

// Power operations
var base := BigInteger(2);
var huge := base.Power(256);
PrintLn('2^256 = ');
PrintLn(huge.ToString);
PrintLn('');

// Modular arithmetic
var modVal := BigInteger('1000000007');
var modResult := a.ModPow(b, modVal);
PrintLn('a^b mod 1000000007 = ' + modResult.ToString);

// GCD - global function
var x := BigInteger(48);
var y := BigInteger(18);
PrintLn('GCD(48, 18) = ' + GCD(x, y).ToString);

// Bit operations
PrintLn('Bit length of 2^256: ' + huge.BitLength.ToString);
?>