#include<stdio.h>
FILE *in=fopen("fact.in","r");
FILE *out=fopen("fact.out","w");
long int n,i,p;
int main()
{
fscanf(in,"%ld",&n);
p=0;
for(i=1;i<=n;i++)
{
if(i%100==25) p++;
if(i%5==0) p++;
}
fprintf(out,"%ld",p);
return 0;
}