1089: highest order of factorial

Title Description

Enter a positive integer n. Output n! The number on the highest digit of .

Input

Enter a positive integer n（n No more than 1000）.

Output

Output n! The number on the highest digit of .

The sample input

1000

Sample output

4

Tips

Be careful double Type overflow problem .

Code ：

//n The factorial 
// Input ：
//1000
// Output ：
//4


#include <stdio.h>
int main ()
{
    double sum=1.0;
    int n,i;
    scanf("%d",&n);
    for(i=1;i<=n;i++)
    {
        sum*=i*1.0;
        while(sum>=10)
        {
            sum=sum/10;
        }
    }
    printf("%.0lf",sum);
    return 0;
}

Running results ：

Submit ：