import java.math.BigInteger;

public class Euler16 {
    static int solve(int exponent) {
        BigInteger val = BigInteger.TWO.pow(exponent);
        int sum = 0;
        for (char c : val.toString().toCharArray())
            sum += c - '0';
        return sum;
    }

    public static void main(String[] args) {
        assert solve(15) == 26 : "Checkpoint failed for exponent=15";
        System.out.println(solve(1000));
    }
}