Thắc mắc số lạ trong C++

#include<stdio.h>
#include<conio.h>
#include<fstream>
using std::ifstream;
using std::ofstream;
using std::endl;
#define in "LEAPYEAR.INP"
#define out "LEAPYEAR.OUT"

int main(){
 ifstream instream;
 ofstream outstream;
 instream.open("LEAPYEAR.INP");
 outstream.open("LEAPYEAR.OUT");
 int a, b,i,h;
 instream>>a>>b>>;
 for (i=a;i<=b;i++){
 if(0==i%19) h=h+1;
 if(3==i%19) h=h+1;
 if(6==i%19) h=h+1;
 if(9==i%19) h=h+1;
 if(11==i%19) h=h+1;
 if(14==i%19) h=h+1;
 if(17==i%19) h=h+1;
 }
 outstream<<"So nam nhuan la: \n"
 <<h
 <<endl;
 instream.close();
 outstream.close();
 return 0;
 }