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program Ch2;
{$mode objfpc}
uses
SysUtils;
function IsPrime(N:Integer):Boolean;
var
I:Integer = 5;
begin
if((N = 2) or (N = 3)) then Exit(True);
if((N <= 1) or (N mod 2 = 0) or (N mod 3 = 0)) then Exit(False);
while I * I <= N do
begin
if((N mod I = 0) or (n mod (I+2) = 0)) then Exit(False);
Inc(I,6);
end;
Exit(True);
end;
function PrimeCount(N:Integer):Integer;
var
I:Integer;
begin
Result := 0;
for I := 1 to N-1 do
if IsPrime(I) then Inc(Result);
end;
begin
WriteLn(PrimeCount(10));
WriteLn(PrimeCount(15));
WriteLn(PrimeCount(1));
WriteLn(PrimeCount(25));
end.
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