#include<stdio.h>
int main()
{
int num,i,k=1;
int count=0;
scanf("%d",&num);
for(i=1;i<=num;i++)
{
k=i*k;
count+=k;
}
printf("%d",count);
return 0;
}
#include<stdio.h>
int main()
{
int num,i,k=1;
int count=0;
scanf("%d",&num);
for(i=1;i<=num;i++)
{
k=i*k;
count+=k;
}
printf("%d",count);
return 0;
}