#include <cstdio>

FILE *in,*out;

using namespace std;

const int L = 26;

int nrcifrezero(int x)
{
		int putere = 5,r = 0;
		while(x != 0)
		{
				r += x/putere;
				x /= 5;
		}
		return r;

}

int cauta(int x)
{
		int pas,r = 0;
		pas = 1 << L;
		while(pas != 0)
		{
				if(nrcifrezero(r + pas) < x)
					r += pas;
				pas /= 2;
		}
		r ++;
		if(nrcifrezero(r) != x)
			return -1;
		return r;
}

int main()
{
		in = fopen("fact.in","r");
		out = fopen("fact.out","w");
    int p;
    fscanf(in,"%d",&p);
		fprintf(out,"%d",cauta(p));


    return 0;
}