#include<iostream>
#include<fstream>

using namespace std;

ifstream in("stergeri.in");
ofstream out("stergeri.out");

int a[100100], b[100100];

int main()
{
	int m, n, res, i;
	
	in >> n >> m >> res;
	
	for(i = 1; i <= m; ++i)
		in >> a[i] >> b[i];
	
	for(i = m; i >= 1; --i)
		if(a[i] <= res)
			res += (b[i] - a[i] +1);
		
	out << res;
	
	return 0;
}