View Code of Problem 73

#include <cstdio>
#include <iostream>

using namespace std;
int peach(int n){//倒数第几天 
	if(n==1)
		return 1;
	else 
		return (peach(n-1)+1)*2; 
}
int main(){
	int n;
	cin>>n;
	cout<<peach(n);
}