#include<iostream.h>

int main()

{

int i,n,j,fa=1,sq=1;

float ans=0.0,sum=0.0;

cout<<"Enter any number : ";

cin>>n;

for(i=1;i<=n;i++)

{

for(j=1;j<=i;j++)

{

fa=fa*j;

sq=sq*i;

}

ans=(float)sq/(float)fa;

if(i%2!=0)

sum+=ans;

else

sum-=ans;

fa=1;

sq=1;

}

cout<<sum;

}