#include <iostream>
#include <fstream>
using namespace std;
ifstream in("stergeri.in");
ofstream out("stergeri.out");
const int MMAX = 100001;
int a[MMAX], b[MMAX];
int main()
{
    int n, m ,k;
    in >> n >> m >> k;
    for( int i = 0 ; i < m ; i ++ )
        in >> a[i] >> b[i];
    for( int i = m - 1; i > -1 ; i-- )
        if( a[i] <= k )
          k += ( b[i] - a[i] + 1 );
    out << k ;
    return 0;
}