#include<stdio.h>
#include<values.h>
#include<math.h>
long long n,m,k;
FILE *f=fopen("stergeri.in","r");
FILE *g=fopen("stergeri.out","w");
void cit() {long long s,x,y,min;
    min=MAXLONG;
	fscanf(f,"%lld, %lld, %lld", &n, &m, &k);
	s=0;
	for(register long i=1; i<=m; i++)
	{	fscanf(f,"%lld, %lld", &x, &y);
		if(min>x)
		min=x;
   		s+=(y-x+1);
	}
	if(k<min)
	fprintf(g,"%lld", k);
	else fprintf(g, "%lld", k+s);
}
int main() {
	cit();
return 0;}