#include <stdio.h>
#define MMAX 100100

int x[MMAX], y[MMAX];

int main ()
{
    int i, N, M, res;

    freopen ("stergeri.in", "r", stdin);
    freopen ("stergeri.out", "w", stdout);

    scanf ("%d%d%d", &N, &M, &res);
    for (i = 1; i <= M; i ++)
        scanf ("%d%d", &x[i], &y[i]);

    for (i = M; i >= 1; i --)
        if (x[i] <= res)
            res = res + y[i] - x[i] + 1;

    printf ("%d", res);
    return 0;
}