ll f(ll a,ll b){
	return a==0||b==0||gcd(a,b)!=1?0:(a-1)*(b-1);
}
{
	ll@n,@a[n];
	if(n==2){
		wt(f(a[0],a[1]));
		wt(1,2);
	}
	if(n==3){
		ll x0=f(f(a[1],a[2]),a[0]);
		ll x1=f(f(a[0],a[2]),a[1]);
		ll x2=f(f(a[0],a[1]),a[2]);
		if(x0<x1&&x0<x2){
			wt(x0);
			wt(2,3);
			wt(1,2);
		}else if(x1<x2){
			wt(x1);
			wt(1,3);
			wt(1,2);
		}else{
			wt(x2);
			wt(1,2);
			wt(1,2);
		}
	}
	if(n>3){
		wt(0);
		wt(1,2);
		wt(1,2);
		rep(i,n-3){
			wt(n-i-3,n-i-2);
		}
	}
}