import java.math.BigInteger;

public class Euler20 {
    static int solve(int n) {
        BigInteger fact = BigInteger.ONE;
        for (int i = 2; i <= n; i++)
            fact = fact.multiply(BigInteger.valueOf(i));
        int sum = 0;
        for (char c : fact.toString().toCharArray())
            sum += c - '0';
        return sum;
    }

    public static void main(String[] args) {
        assert solve(10) == 27 : "Checkpoint failed for n=10";
        System.out.println(solve(100));
    }
}