#include <stdio.h>
#include <math.h>

long long n, m, r, i, v[1 << 17];

int main() {
	freopen("grigo.in", "r", stdin);
	freopen("grigo.out", "w", stdout);
	scanf("%lld%lld", &n, &m);
	r = 1;
	while(scanf("%lld", &m) == 1) {
		v[m] = 1;
	}
	for(;n--; ++i) {
		if(!v[i + 1]) {
			r = r * i % 1000003;
		}
	}
	printf("%lld\n", r);
	return 0;
}