#include <bits/stdc++.h>
using namespace std;
int bin(long long n)
{
long long z=1;
if(n==0)
z=0;
for(int i=1;i<=n;i++)
{
z=z*i;
}
return z;
}
int main()
{
std::ios_base::sync_with_stdio(NULL);
cin.tie(NULL);
cout.tie(NULL);
long long n,m;
cin>>n;
m=bin(n);
cout<<m;
return 0;
}
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