#include<cstdio>   
  
using namespace std;   
  
long i, pow5_p[14], pow5[14], p, sol = 1, p1, sol1, sol2, s;   
  
long binary_search(long val)   
{   
    long j, step;   
       
    for(step = 1; step < 12; step <<= 1);   
    for(j = 1; step; step >>= 1)   
        if(j + step < 12 && pow5_p[j + step] <= val)   
            j += step;   
       
    return j;   
}   
  
int main()   
{   
    freopen("fact.in","r",stdin);   
    freopen("fact.out","w",stdout);   
       
    scanf("%ld", &p);   
       
    if(p == 0)   
    {   
        printf("1\n");   
        return 0;   
    }   
    pow5[0] = 1;   
    for(i = 1; i <= 12; ++i)   
    {   
        pow5_p[i] = pow5_p[i - 1] + sol;   
        sol *= 5;   
        pow5[i] = sol;   
    }   
    sol = 0;   
    p1 = p;   
    while(p1)   
    {   
        sol += pow5[binary_search(p1)];   
        p1 -= pow5_p[binary_search(p1)];   
    }   
    p1 = sol;
	s = 0;
	while(p1)
	{
		s += (p1 / 5);
		p1 /= 5;
	}
	/*while(p1)   
    {   
        sol1 += pow5[binary_search(p1)];   
        p1 -= pow5_p[binary_search(p1)];   
        sol2 = sol - sol1;   
        for(i = 1;i <= 12; ++i)   
            if(sol2 == pow5[i])   
                if(pow5_p[binary_search(p1)] < pow5_p[i])   
                {   
                    printf("-1\n");   
                    return 0;   
                }   
    }   
    for(i = 1;i <= 12; ++i)   
        if(sol == pow5[i])   
            if(pow5_p[binary_search(p)] < pow5_p[i])   
            {   
                printf("-1\n");   
                return 0;   
            }*/
	if(s == p)
		printf("%ld\n", sol);
	else
		printf("-1\n");
	
    return 0;   
}