Something

 public static DevInt pow(DevInt x, int p) {
        if (p == 1) { return x; }
        if (p <= 0) {
            return new DevInt();
        } 
        if (p%2==0) {
           return pow(x * x, p / 2); 
        }
        else {
            return x*pow(x*x,(int)Math.Floor((double)p/2));
        }
    }