#include <iostream>
#include <cmath>
using namespace std;
int main() {
long long n;
long long route;
cin>>n;
if(n==1){
cout<<1;
}
else{
for(long long i=1;i<n;i++){
if(n>=3*pow(i,2)-9*i+8){
if(n<=3*pow(i,2)-3*i+1){
cout<<i;
}
}
}
}
return 0;
}
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