import std.stdio;

void main()
{
    ulong p = 1;
    ulong n = 2;
    ulong sum = 0;
    ulong temp;

    while (n < 4e9)
    {
        sum += n;

        temp = p + 2*n;
        n = 2*p + 3*n;
        p = temp;;
    }

    writeln(sum);
}