import sys
input = sys.stdin.readline

N,mod=list(map(int,input().split()))

ANS=N-1

if (N-1)%2==0:
    ANS//=2
else:
    if mod%2==0:
        print("NaN")
        exit()
    else:
        ANS=ANS*pow(2,-1,mod)%mod

print(ANS)