#include <stdio.h>

int main(void) {
	int n;
	int c;
	int i;
	int cake;
	int ans = 0;

	scanf("%d %d", &n, &c);
	for (i = 0; i < c; i++) {
		scanf("%d", &cake);
		ans += cake;
	}
	if (ans % (n + 1) != 0) {
		printf("%d\n", ans / (n + 1) + 1);
	}
	else {
		printf("%d\n", ans / (n + 1));
	}

	return 0;
}
