#include<fstream.h>

int main()
{ unsigned long n,m,k,i,s=0,x1,x2;
  ifstream f("stergeri.in");
  ofstream g("stergeri.out");
  f>>n>>m>>k;
  for(i=1;i<=m;i++)
	{  cin>>x1>>x2;
	   s+=(x1-x2)+1;
	}
  g<<s+k;
  return 0;
  }