#!/usr/bin/env python3


def main():
    n, c = (int(x) for x in input().split())

    dp = [[0] * n for _ in range(n)]

    for i in reversed(range(n)):
        for j in range(i + 1, n):
            dp[i][j] = min(
                max(
                    dp[i][k] + k + 1,
                    dp[k + 1][j] + c,
                )
                for k in range(i, j)
            )

    print(dp[0][-1])


if __name__ == "__main__":
    main()