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  1. program fermath_test_for_prime_numbers;
  2. function bigmultiplication(x,y,n:longint):longint;
  3. var 
  4. doi:longint;
  5. begin
  6. 	doi:=0;
  7. 	while(y>0) do
  8. 	begin
  9. 		if(y mod 2 =1) then
  10. 		begin
  11. 			doi:=(doi+x)mod n;
  12. 		end;
  13.  
  14. 		x:=(2*x)mod n;
  15. 			y:=y div 2;
  16. 	end;
  17. 	bigmultiplication:=doi;
  18. end;
  19.  
  20.  
  21.  
  22.  
  23. function exponents_mod_n(x,y,n:longint):longint;
  24. var
  25. doi,doing:longint;
  26. begin
  27. 	doing:=x;
  28. 	doi:=1;
  29. 	while(y>0) do
  30. 	begin
  31. 		if(y mod 2 =1) then
  32. 		begin
  33. 			doi:=bigmultiplication(doi,doing,n);
  34. 		end;
  35. 		doing:=bigmultiplication(doing,doing,n);
  36. 			y:=y div 2;
  37. 	end;
  38. 	exponents_mod_n:=doi;
  39. end;
  40. var
  41. a,p,x,n:longint;
  42. i,flag:integer;
  43. begin
  44. 	Randomize;
  45.  
  46. 	readln(p);
  47. 	flag:=0;
  48. 	if p mod 2 = 0 then
  49. 		begin
  50. 		writeln('the number is composite');
  51.  
  52. 		end;
  53. 	for i:=1 to 7 do
  54. 	begin
  55.  
  56.  
  57. 		x:=p-1;
  58. 		a:=random(x)+1 mod x;
  59. 		n:=exponents_mod_n(a,x,p);
  60. 		if n<>1 then
  61. 		begin
  62. 		writeln('the number is composite');
  63. 		flag:=1;
  64. 		break;
  65. 		end;
  66.  
  67. 	end;
  68. 	if flag = 0 then
  69. 	writeln('this is prime number');
  70. end.
  71.  
stdin
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239
compilation info 
Free Pascal Compiler version 2.2.0 [2009/11/16] for i386
Copyright (c) 1993-2007 by Florian Klaempfl
Target OS: Linux for i386
Compiling prog.pas
Linking prog
70 lines compiled, 0.0 sec
stdout
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this is prime number
https://ideone.com/s9jcz
language:
Pascal (fpc 3.0.4)
created:
12 years ago
visibility:
secret

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