#include <fstream>
#include <algorithm>
using namespace std;
ifstream cin("stergeri.in");
ofstream cout("stergeri.out");

struct seg
{
    long long st,dr;
} v[100001];
int n, m , poz ;
int main()
{
    cin >> m >> n >> poz ;
    long long last = -1e18;
    for ( int i = 1; i <= n ; i ++ )
        cin >>v[i].st>>v[i].dr;


        for ( int i = n ; i >= 1; i -- )
        {
            if ( v[i] . st <= poz )
                poz += v[i].dr - v[i].st + 1;
        }

        cout << poz << '\n';

    return 0;
}