#include<stdio.h>
int main()
{
    int  fact = 1, nr = 0, p, i = 2, u, k;
    printf("p = ");
    scanf("%d", &p);
    if ( p == 0)printf("n = 1");
    else
    {
        while(nr <= p )
        {
            fact  = fact * i;
            i ++;
            while(u == 0)
            {
                nr ++;
                fact =  fact / 10;
                u = fact % 10;
            }
        }
    }
    printf("n = %d", i+1);
    return 0;

}