import sys
sys.setrecursionlimit(100000000)
MOD = 10 ** 9 + 7
INF = 10 ** 15

def main():
    N,K = map(int,input().split())
    if N%2 == 0:
        if K%2 == 0:
            if 2*K < N:
                ans = K + 1
            else:
                ans = N//2
        else:
            if 2*K < N:
                ans = K + 1
            else:
                ans = N//2
    else:
        ans = min(K + 1,N)
    print(ans)
if __name__ == '__main__':
    main()