#include<iostream>
#include<fstream>
using namespace std;
ifstream f("fractii.in");
ofstream o("fractii.out");
int n,i,j,k,p,q,a,c;
bool ok;
int main(){
f>>n;c=0;
p=1;
q=1;
while(p<=n){
if(p>q) a=q;
else a=p;
ok=1;
if(p==q&&p>1) ok=0;
else if(p%a==0&&q%a==0&&a>1) ok=0;
else {if(p%2==0&&q%2==0){
ok=0;
} else {
for(k=3;k<=a/2;k=k+2){
if(p%k==0&&q%k==0){
ok=0;break;
}
}
}
}
if(ok==1){
c++;

cout<<p<<" "<<q<<'\n';
}
if(q<n) q++;
else {p++;q=1;}
}
o<<c;
}