include <bits/stdc++.h>

using namespace std; int A[10005], B[105];

int main() {

int n, m;
cin >> n >> m;
for (int i = 1; i <= n; i++) {
	cin >> A[i];
}
for (int i = 1; i <= m; i++) {
	B[i] = A[i];
}
for (int i = m; i <= n; i++) {
	sort(B, B + m);
	B[0] += A[i];
}
sort(B, B + m);
cout << B[m - 1];
return 0;

}