#include<stdio.h>
int main()
{long sum,p,i;sum=0;p=1;for(i=1;i<=20;i++){p*=i;sum+=p;}printf("1!+2!+3!+...+20!=%ld\n",sum);
return 0;
}
#include<stdio.h>
int main()
{long sum,p,i;sum=0;p=1;for(i=1;i<=20;i++){p*=i;sum+=p;}printf("1!+2!+3!+...+20!=%ld\n",sum);
return 0;
}