#include <fstream>
using namespace std;

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

int v[1000001][4], i, j, k, ok, minim;
int n, x, m, y;

int main(){
    fin >> n >> m >> k;
    for(i = 1; i <= n; i ++){
        fin >> x >> y;
        v[i][1] = y - x + 1;
        v[i][2] = x;
    }
    for(i = m; i >= 1; i --){
        if(v[i][2] < k)
            k += v[i][1];
    }
    fout << k;
    return 0;
}