#include<fstream.h>

int main()
{ unsigned long n,m,k,i,x1,x2,xk,b[100]={0},j,aux;
  ifstream f("stergeri.in");
  ofstream g("stergeri.out");
  f>>n>>m>>k;xk=k;
  f>>x1>>x2;
  for(j=x1;j<=x2;j++)
	b[j]=1;
  xk+=(x2-x1)+1;
  for(i=2;i<=m;i++)
	{ f>>x1>>x2;aux=x2;
	  if(x1<xk)
		{for(j=x1;j<=x2;j++)
			if(b[j]==1) x2++;
			else b[j]=1;
		 xk+=(aux-x1)+1;}
	}
  j=0;
  for(i=0;j!=k;i++)
	if(b[i]==0)
		j++;
  g<<i;
  return 0;
  }