import java.util.Scanner;
public class Main {
public static long factorial(int n) {
if (n < 0) {
return 0; // Factorial is not defined for negative numbers
}
long result = 1;
for (int i = 2; i <= n; i++) {
result = result * i;
}
return result;
}
public static void main
(String[] args
) { Scanner scanner
= new Scanner
(System.
in);
int n = scanner.nextInt();
System.
out.
println(factorial
(n
));
scanner.close();
}
}
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