// coverts decimal to binary
// vishesh
// 21/05/2005
 
#include <iostream>
 
char* DEC_BIN(int);
 
int main()
{
	//
	int num;
	std::cout << "Enter a number: ";
	std::cin   >> num;
	std::cout << DEC_BIN(num);
	std::cin.get();
	return 0;
}
 
char* DEC_BIN(int dec)
{
	using namespace std;
 
	char *rtn;
 
	int prev, len, temp, *bin;
 
	prev = dec;
 
	for(int i=0;prev!=0;i++)
	{	
		prev = prev/2;
		len=i;
	}
 
	bin = new int[len+1];
 
	prev = dec;
 
	for(int i=0;prev!=0;i++)
	{
		bin[i] = prev%2;
		prev = prev/2;
		len=i;
	}
 
	bin[len+1] = prev%2;
	len++;
 
	for(int i=0;i<len/2;i++)
	{
		temp=bin[i];
		bin[i]=bin[len-1-i];
		bin[len-1-i]=temp;
	}
 
	rtn = new char[len+1];
 
	for(int i=0;i<len;i++)
	{
		rtn[i]=bin[i]+'0';
		rtn[i+1]='\0';
	}
 
	return rtn;
}