/// <summary>
/// nが大きくてkが小さいときに使える。
/// </summary>
/// <param name="n"></param>
/// <param name="k"></param>
/// <returns></returns>
static Mint nCk(long n, long k)
{
Mint x = 1;
Mint y = 1;
for (int i = 0; i < k; i++)
{
x *= n - i;
y *= i + 1;
}
return(x / y);
}
public static Mint Pow(Mint a, long n)
{
if (n == 0)
{
return(new Mint(1));
}
Mint b = Pow(a, n >> 1);
b *= b;
if ((n & 1) == 1)
{
b *= a;
}
return(b);
}
public static void Abc156_D()
{
long n = rl;
long a = rl;
long b = rl;
var total = Mint.Pow(2, n) - 1;
var a1 = nCk(n, a);
total -= a1;
var b1 = nCk(n, b);
total -= b1;
Console.WriteLine(total);
}
public static Mint Inv(Mint n)
{
long a = n.Value;
long b = MOD;
long x = 1;
long u = 0;
while (b != 0)
{
long k = a / b;
long _x = u;
u = x - k * u;
x = _x;
long _a = a;
a = b;
b = _a - (k * b);
}
return(new Mint(x));
}