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  1. program cntprim (input,output);
  2.     var N , i, j ,m , counter : integer;
  3.         a : array [1..5000000] of boolean;
  4. begin
  5.     read(N);
  6.     for i:=1 to N do a[i]:=true;
  7.     m:=trunc(sqrt(N));
  8.     for i:=2 to m do 
  9.       if a[i] then for j:=2 to N div i do a[i*j]:=false;
  10.     counter:=0;
  11.     for i:=2 to N do if a[i] then counter:=counter+1;
  12.     writeln(counter);    
  13. end.
Success #stdin #stdout 0.01s 9000KB
comments (?)
stdin 
29
stdout 
10
https://ideone.com/urHpY
language:
Pascal (gpc 20070904)
created:
14 years ago
visibility:
public

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