#include <fstream>

using namespace std;
ifstream f("stergeri.in");
ofstream g("stergeri.out");
int n,e,k,i,x[101000], y[101000];

int main()
{
	f>>n>>e>>k;
	for(i=1;i<=e;i++) f>>x[i]>>y[i];
	for(i=e;i>=1;i--) if(x[i]<=k) k+=y[i]-x[i]+1;
	g<<k;
	return 0;
}