#include<stdio.h>
int n,m,k,h[100000][3],v[2000000];
void parc()
{
	for(int i=1;i<=k;++i)
		v[i]=i;
}
void citire()
{
	for(int i=1;i<=m;++i)
		for(int j=1;j<=2;++j)
			scanf("%d",&h[i][j]);
}
void calcul()
{
	int rez=k;
	for(int i=m;i;--i)
		rez=rez+(h[i][2]-h[i][1]+1);
	printf("%d",rez);
}
int main()
{
	freopen("stergeri.in","r",stdin);
	freopen("stergeri.out","w",stdout);
	scanf("%d%d%d",&n,&m,&k);
	parc();
	citire();
	calcul();
	return 0;
}