#include <cstdio>

using namespace std;

int n=100000000;
int p;
int lg = 134217728;

int zero(int x)
{
    int s=0;
    while(x/5 != 0)
        {s+=(x/5); x/=5;}
    return s;
}

int cautbin(int p, int l)
{
    int i;
    for(i=n; l!=0; l>>=1)
        if(i - l > 0 && zero(i-l) >= p)
        {
            i-=l;
            if(zero(i-l) == p)
                return i;
        }
    return i;
}


int main()
{
    freopen("fact.in", "r", stdin);
    freopen("fact.out", "w", stdout);
    scanf("%d", &p);
    printf("%d ", cautbin(p, lg));
    return 0;
}