#include<cstdio>

using namespace std;

inline int zeros(int x)
{
    int a=0;
    while(x)
    {
        a+=x/5;
        x/=5;
    }
    return a;
}

inline int binarysearch(int x)
{
    int step=1<<30 ,i;
    for(i=1<<30;step;step>>=1)
        if(zeros(i-step)>=x)
            i-=step;
    if(zeros(i)==x)
        return i;
    return -1;
}

int main()
{
    freopen("fact.in","r",stdin);
    freopen("fact.out","w",stdout);
    int i,j,x;
    scanf("%d",&x);
    if(x==0)
        printf("1");
    else
        printf("%d",binarysearch(x));
}