#include<stdio.h>
#include<conio.h>
int main()
{
int i, n;
long P;
i = 1;
P = 1;
do
{
printf("\nNhap n: ");
scanf("%d", &n);
if(n < 1)
{
printf("\nN phai lon hon hoac bang 1. Xin nhap lai !");
}
}while(n < 1);
while(i < n)
{
P = P * i;
i++;
}
printf("\nTich 1x2x....x%d la: %ld", i, P);
getch();
return 0;
}