#include <bits/stdc++.h>
using namespace std;
const int N = 10001 ;
struct bigNumber{//结构体名称 X = 23485762384567823 X[1] =
int len , x[N] ;
bigNumber() { memset(x, 0 , sizeof(x) ) ;len = 1; }
void print() { for (int i = len;i;i--) printf("%d", x[i]) ;puts("") ; }
} ;
bigNumber fix(bigNumber a ){
for (int i = 1;i<a.len ;i++) {
a.x[i+1] += a.x[i] / 10 ;
a.x[i] %= 10 ;
}
while (a.x[a.len] >= 10 ) {
a.x[a.len+1] += a.x[a.len ] / 10 ;
a.x[a.len] %= 10 ;
a.len ++ ;
}
return a ;
}
inline bigNumber operator *(bigNumber a, int b) {//126545234554345676543265434565 * 65498
for (int i = 1;i<=a.len;i++) a.x[i] *= b;
return fix(a) ;Z
}
inline bigNumber operator +(bigNumber a, bigNumber b){
bigNumber c ;
c.len = max(a.len , b.len) ;Z
for (int i = 1;i<=c.len ;i++) c.x[i] = a.x[i] + b.x[i] ;
return fix(c) ;
}
int main(){
int n;
cin>> n;
bigNumber a,b;
a.x[1]= 1; b.x[1] = 0 ;
for (int i =1;i<=n;i++) a= a*i, b= b+a ;
b.print() ;//B的输出
return 0 ;
}
/*
#include <bits/stdc++.h>
using namespace std;
const int N = 10001 ;
struct bigNumber{
int len , x[N] ;
bigNumber() { memset(x, 0 , sizeof(x)) ;len = 1; }
void print() { for (int i = len;i;i--) printf("%d", x[i]) ;puts("") ; }
} ;
bigNumber fix(bigNumber a )
{
for (int i = 1;i<a.len ;i++) {
a.x[i+1] += a.x[i] / 10 ;
a.x[i] %= 10 ;
}
while (a.x[a.len] >= 10 ) {
a.x[a.len+1] += a.x[a.len ] / 10 ;
a.x[a.len] %= 10 ;
a.len ++ ;
}
return a ;
}
inline bigNumber operator *(bigNumber a, int b)
{
for (int i = 1;i<=a.len;i++) a.x[i] *= b;
return fix(a) ;
}
inline bigNumber operator +(bigNumber a, bigNumber b)
{
bigNumber c ;
c.len = max(a.len , b.len) ;
for (int i = 1;i<=c.len ;i++) c.x[i] = a.x[i] + b.x[i] ;
return fix(c) ;
}
int main()
{
int n;
cin>> n;
bigNumber a,b;
a.x[1]= 1; b.x[1] = 0 ;
for (int i =1;i<=n;i++) a= a*i, b= b+a ;
b.print() ;
return 0 ;
}
*/