#include <stdio.h>
int main()
{
	freopen("stergeri.in","r",stdin);
	freopen("stergeri.out","w",stdout);
	long long m,n,k;
	long long a,b,rasp=0;
	scanf("%lld %lld %lld",&m,&n,&k);
	int i;
	rasp=k;
	for (i=1;i<=n;i++)
	{
		scanf("%lld",&a);
		scanf("%lld",&b);
		if (rasp<b && rasp>a)
		{
			rasp+=b-a+1;
		}
	}
	printf("%lld",rasp);
	return 0;
}