#include <stdio.h>
long x[100002],y[100002],i,n,m,k,sol;
int main(){
	FILE *f,*g;
	f=fopen("stergeri.in","r");
	g=fopen("stergeri.out","w");
	fscanf(f,"%ld%ld%ld",&n,&m,&k);
	for(i=1;i<=n;i++)
		fscanf(f,"%ld%ld",&x[i],&y[i]);
	sol=k;
	for(i=n;i>0;i--)
		if(x[i]<=k) sol+=y[i]-x[i]+1;
	fprintf(g,"%ld\n",sol);
	fclose(f);
	fclose(g);
	return 0;
}