import java.util.Scanner; //三位阶乘和数
public class test {
public static void main(String[] args) { double sum=1;
for(int i=1;i<=63;i++){
sum=sum+f(i);
}
System.out.println("sum="+sum);
}
public static double f(int n){
double m;
if(n==1){
m=2;
}else{
m=2*f(n-1);
}
return m;
}