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#include <stdio.h>
#include <string.h>
#define MAX 10000
#define mod 10000
#define baselen 4
#define in(a) scanf("%d",&a)
#define out1(a) printf("%d",a)
#define out2(a) printf("%04d",a)
typedef int type;
struct bint{
 type dig[MAX], len;
 bint(){len = 0, dig[0] = 0;}
};
void by(bint a, type b, bint& c){
 type i, carry;
 for( i = carry = 0; i <= a.len || carry; i++){
 if( i <= a.len ) carry += b*a.dig[i];
 c.dig[i] = carry%mod;
 carry /= mod;
 }
 i--;
 while( i && !c.dig[i] )i--;
 c.len = i;
}
bool input(bint& a){
 type i, j, w, k, p;
 char data[MAX*baselen+1];
 if(scanf("%s",data)==EOF)return false;
 w = strlen(data) - 1, a.len = 0;
 for(p=0;p<=w&&data[p]=='0';p++);
 while(1){
 i = j = 0, k = 1;
 while(i<baselen&&w>=p){
 j = j+ (data[w--] - '0')*k;
 k *= 10, i++;
 }
 a.dig[a.len++] = j;
 if(w<p)break;
 }
 a.len--;
 return true;
}
void output(bint& a){
 type i;
 i = a.len - 1;
 out1(a.dig[a.len]);
 while(i>=0)out2(a.dig[i--]);
}
void give(type a, bint& b){
 b.dig[0] = a%mod;
 a /= mod;
 if(a>0)b.dig[1] = a, b.len = 1;
 else b.len = 0;
}
int main()
{
 bint a;int b,i;scanf("%d",&b);give(1,a);
 for(i=2;i<=b;i++)by(a,i,a);
 output(a);printf("\n");
 return 0;
}