#include <stdio.h>
FILE *f=fopen("fact.in","r"), *g=fopen("fact.out","w");
int main()
{
long n,i=0,k5=0;
fscanf(f,"%ld",&n);
while (k5<n)
{
i+=5;
k5++;
}
fprintf(g,"%ld\n",i);
return 0;
}