#include <fstream>

using namespace std;

long a[100010],b[100010],n,m,k;

ifstream fin ("stergeri.in");
ofstream fout("stergeri.out");

void citire()
{
	    fin>>n>>m>>k;
		for (int i=0;i<m;i++)
			   fin>>a[i]>>b[i];
	fin.close();
}

void numar ()
{
	  for (int i=m-1;i>=0;i--)
		  if (a[i]<=kk)
			  k+=b[i]-a[i]+1;
}


int main ()
{
	   citire();
	   numar();
	   fout<<k<<"\n";
	   fout.close();
	   return 0;
}