#include <fstream>

using namespace std;

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

const int NMAX = 2000000000;
const int MMAX = 100000;

int N, M, K;
int v[MMAX+2], a[MMAX+2];

int main() {
    in >> N >> M >> K;
    for( int i= 1;  i<=M;  ++i ) {
        in >> a[i] >> v[i];
    }
    for( int i= M;  i>0;  --i ) {
        if( a[i] <= K )  K+= (v[i]-a[i]+1);
    }
    out << K << '\n';
    return 0;
}