include

using namespace std; int s[11000], ans;

int main() {

int n, m;
cin >> n >> m;

for (int i = 1; i <= n; i++) {

	cin >> s[i];
}

int t = m + 1;

while (t <= n + m) {
	for (int i = 1; i <= m; i++) {

		s[i]--;

		if (s[i] == 0) {
			s[i] = s[t];
			t++;
		}
	}

	ans++;
}

cout << ans;
return 0;

}