#include <cstdio>

int a[100001][2], n, m, K;

int main()
{
    freopen("stergeri.in","r",stdin);
    scanf("%d %d %d\n", &n, &m, &K);
    int i;
    for(i = 1; i <= m; ++i) scanf("%d %d\n", &a[i][0], &a[i][1]);

    int sol = K;

    for(i = m; i >= 1; --i)
	if(a[i][0] <= sol) sol += a[i][1] - a[i][0] +1;

    freopen("stergeri.out","w",stdout);
    printf("%d\n", sol);

    return 0;
}