#include<cstdio>
#define N 100000000
int p,i,j,t,s,k,l;
int main()
{freopen("fact.in","r",stdin);
freopen("fact.out","w",stdout);
scanf("%d",&p);
for(s=1;s<=N;s<<=1);
for(;s;s>>=1)
if(s+i<=N)
       {j=5*(i+s),t=0;
       for(k=5;k<=j;k*=5)
             t=t+j/k;
       if(t<=p)
             i+=s,l=t;}
if(!p)
       printf("1");
else
       if(l==p)
               printf("%d",5*i);
       else
               printf("-1");
return 0;}