include <bits/stdc++.h>

using namespace std; string jiecheng(int n){

char a[300];
a[0]='1';
int len=1;
for(int i=2;i<=n;i++){
	int jin=0;
	for(int j=0;j<len;j++){
		int t= i*(a[j]-'0')+jin;
		jin=t/10;
		a[j]=t%10+'0';
	}
	while(jin>0){
		a[len]=jin%10+'0';
		len++;
		jin=jin/10;
	}
}
string s="";
for(int i=len-1;i>=0;i--){
	s=s+a[i];
}
return s;

} string jia(string s1,string s2){

char s3[300];
if(s1.length()<s2.length()){
	swap(s1,s2);
}

int len1=s1.length();
int len2=s2.length();
for(int i=0;i<len1-len2;i++ ){
	s2="0"+s2;
}
int jin=0;
for(int i=len1-1;i>=0;i--){
	int t=s1[i]-'0'+s2[i]-'0'+jin;
	jin=t/10;
	s3[i]=t%10+'0';
}
string ss="";
if(jin>0){
	ss=ss+"1";
}
for(int i=0;i<len1;i++){
	ss=ss+s3[i];
}
return ss;

} int main() {

string s1="0",s2;
int n;
cin>>n;
for(int i=1;i<=n;i++){
	s2=jiecheng(i);  //算阶乘 
	s1=jia(s1,s2);   //算加 
}
cout<<s1;
return 0;

}