#include<stdio.h>
using namespace std;
FILE*in=fopen("fact.in","rt");
FILE*out=fopen("fact.out","wt");
int q ,p,i,k,x;
int main()
{
fscanf(in,"%d",&p);
if(p%6==5)
fprintf(out,"-1");
else
{
x=p/6;
for(i=1;i<25;i++)
{
    if(i%5==0)
    k++;
    if(k==p-p%6)
    break;
}

q=25*x+k*5;
fprintf(out,"%d",q);
}
fclose(out);
fclose(in);
return 0;
}