#include <cstdio>
#include <cctype>
#include <numeric>

using namespace std;
const int NMAX = 1e6;
long long n, ans, phi[NMAX + 1];

//==========================================================

class InParser
{
private:
	FILE *fin;
	char *buff;
	int sp;

	char read_ch()
	{
		++sp;
		if (sp == 4096)
		{
			sp = 0;
			fread(buff, 1, 4096, fin);
		}
		return buff[sp];
	}

public:
	InParser(const char* nume)
	{
		fin = fopen(nume, "r");
		buff = new char[4096]();
		sp = 4095;
	}

	InParser& operator >> (int &n)
	{
		char c;
		while (!isdigit(c = read_ch()) && c != '-');
		int sgn = 1;
		if (c == '-')
		{
			n = 0;
			sgn = -1;
		}
		else
		{
			n = c - '0';
		}
		while (isdigit(c = read_ch()))
		{
			n = 10 * n + c - '0';
		}
		n *= sgn;
		return *this;
	}

	InParser& operator >> (long long &n)
	{
		char c;
		n = 0;
		while (!isdigit(c = read_ch()) && c != '-');
		long long sgn = 1;
		if (c == '-')
		{
			n = 0;
			sgn = -1;
		}
		else
		{
			n = c - '0';
		}
		while (isdigit(c = read_ch()))
		{
			n = 10 * n + c - '0';
		}
		n *= sgn;
		return *this;
	}
};

class OutParser
{
private:
	FILE *fout;
	char *buff;
	int sp;

	void write_ch(char ch)
	{
		if (sp == 50000)
		{
			fwrite(buff, 1, 50000, fout);
			sp = 0;
			buff[sp++] = ch;
		}
		else
		{
			buff[sp++] = ch;
		}
	}


public:
	OutParser(const char* name)
	{
		fout = fopen(name, "w");
		buff = new char[50000]();
		sp = 0;
	}
	~OutParser()
	{
		fwrite(buff, 1, sp, fout);
		fclose(fout);
	}

	OutParser& operator << (int vu32)
	{
		if (vu32 <= 9)
		{
			write_ch(vu32 + '0');
		}
		else
		{
			(*this) << (vu32 / 10);
			write_ch(vu32 % 10 + '0');
		}
		return *this;
	}

	OutParser& operator << (long long vu64)
	{
		if (vu64 <= 9)
		{
			write_ch(vu64 + '0');
		}
		else
		{
			(*this) << (vu64 / 10);
			write_ch(vu64 % 10 + '0');
		}
		return *this;
	}

	OutParser& operator << (char ch)
	{
		write_ch(ch);
		return *this;
	}
	OutParser& operator << (const char *ch)
	{
		while (*ch)
		{
			write_ch(*ch);
			++ch;
		}
		return *this;
	}
};

//==========================================================

void genPhi()
{
	int i, j;
	iota(phi, phi + NMAX + 1, 0);
	//
	for(i = 2; i <= NMAX; ++i)
		if(phi[i] == i)
			for(j = i; j <= NMAX; j += i)
				phi[j] = phi[j] / i * (i - 1);
}

int main()
{
	InParser f("fractii.in");
	OutParser g("fractii.out");
	//
	genPhi();
	f >> n;
	n++;
	while(n--)
		ans += phi[n] * 2;
	g << ans - 1;
	return 0;
}