#include <fstream.h>
int main(){
	unsigned long a[100],n,x,y,i,k,m,s=0;
	ifstream in("stergeri.in");
	ofstream out("stergeri.out");
	in>>n>>m>>k;
	for(i=0;i<m;i++){
		in>>x>>y;
		s+=y-x+1;
	}
	out<<k+s;
	return 0;
}