#include <bits/stdc++.h>

using namespace std;

const int MAX_N = 500 + 5;
const int INF32 = 1e9;

int N, M;
int f[2][MAX_N][MAX_N];

int main() {
    scanf("%d%d", &N, &M);
    if (N == M) return printf("0\n"), 0;
    for (int m = 1; m <= M; m ++) {
        for (int n = m + 1; n <= N; n ++) {
            f[m & 1][n][1] = f[~m & 1][n - 1][n - m + 1];
            for (int x = 2, y = 1; x <= n - m + 1; x ++) {
                static auto get = [&] (int y) {
                    return max(f[m & 1][n][y], f[m & 1][n - y][x - y]);
                };
                for (; y + 1 < n - m && y + 1 < x && get(y) > get(y + 1); y ++);
                f[m & 1][n][x] = 1 + get(y);
            }
            // printf("m=%d, n=%d, f=%d\n", m, n, f[m & 1][n][n - m + 1]);
        }
    }
    printf("%d\n", f[M & 1][N][N - M + 1]);
    // fprintf(stderr, "clock=%d\n", clock());
    return 0;
}