代码如下

#include<bits/stdc++.h>
#define ll __int128
using namespace std;
ll s,sum=0;
ll in() {
	ll x=0,w=1;
	char ch=getchar();
	while(ch<'0'||ch>'9') {
		if(ch==-1) w=-w;
		ch=getchar();
	}
	while(ch>='0'&&ch<='9') {
		x=x*10+ch-'0';
		ch=getchar();
	}
	return w*x;
}
void out(ll x) {
	if(x<0) putchar('-'),x=-x;
	if(x>9) out(x/10);
	putchar(x%10+'0');
}
ll js(ll num) {
	ll xxs=1;
	for(ll i=1;i<=num;++i) xxs*=i;
	return xxs;
}
int main() {
    s=in();
    for(ll i=1;i<=s;++i) sum+=js(i);
	out(sum);
    return 0;
}