#include <cstdio>

#define file_in "stergeri.in"
#define file_out "stergeri.out"

int n,m,k,p,l,x,y;

int main()
{
	freopen(file_in,"r",stdin);
	freopen(file_out,"w",stdout);
	
	scanf("%d %d %d", &n,&m,&k);
	
	l=k;
	p=k;
	
	while(m--)
	{
		scanf("%d %d", &x,&y);
		if (x<k)
		{
			p=p+y-x+1;
		}
	}
	
	printf("%d\n", p);
	
	fclose(stdin);
	fclose(stdout);
	
	return 0;
}