C++ :

#include<iostream>
#include<cmath>
using namespace std;
bool prime(int n)
{
	int i,t=sqrt(n);
	for (i=2; i<=t; i++)
		if (n%i==0) break;
	return i>t;
}
int main()
{
	int n;
	cin>>n;
	if (prime(n)) cout<<"T"<<endl;
	else cout<<"F"<<endl;
	return 0;
}

Pascal :

program p2682(input,output);
var
  n,i,f:longint;
begin
  readln(n);
  f:=0;
  for i:=1 to trunc(sqrt(n)) do
    begin
      if (n mod i=0) then
        begin
          f:=1;
          break;
        end;
    end;
  if (f=0) then
    writeln('T')
  else
    writeln('F');
end.