#include<iostream> #include<cstdio> using namespace std; int main(){ //freopen("statistics.in","r",stdin); //freopen("statistics.out","w",stdout); long int n,p=0; cin>>n; for(int i=1;i<n/10;i+=1){ for(int o=1;o<(n-i*10)/5;o++){ p++; } } cout<<p; }