#include <bits/stdc++.h>
using namespace std;
const int NMAX=1e3+5, KMAX=4e4+5;
int v[NMAX], n, k;
struct swp{int i, j;}ans[KMAX];
struct srt{int v, o;}ord[NMAX];
bool cmp(srt a, srt b){return a.v<b.v;}
void solve1()
{
for(int i=1;i<=n;i++)
ord[i]={v[i], i};
sort(ord+1, ord+n+1, cmp);
for(int i=n;i>1;i--)
{
//xor each nr with the next except v[i]
for(int j=1;j<i;j++)
{
v[j]^=v[j+1];
ans[++k]={j, j+1};
}
//make the part before the maximum's position be max^v[j]
for(int j=ord[i].o-2;j>=1;j--)
{
v[j]^=v[j+1];
ans[++k]={j, j+1};
}
//make the part after the maximum's position be max^v[j], with max on v[n]
for(int j=ord[i].o+1;j<=i;j++)
{
v[j]^=v[j-1];
ans[++k]={j, j-1};
}
//decrease the 'positions' of future maximums
for(int j=1;j<i;j++)
if(ord[j].o>ord[i].o)
ord[j].o--;
}
//restore the original values
for(int i=n-1;i>=1;i--)
{
v[i]^=v[i+1];
ans[++k]={i, i+1};
}
}
void solve2(int l, int r, int b)
{
//base case
if(l==r || b<0)
return;
//check for 0 and 1
int f1=l-1, ok0=0;
for(int i=l;i<=r;i++)
if((v[i]&(1<<b))==0)
ok0=1;
else if(f1==l-1)
f1=i;
if(f1==l-1 || ok0==0)
{
solve2(l, r, b-1);
return;
}
//make all (0, 1) before first (1, 1)
for(int i=l;i<=f1-2;i++)
{
v[i]^=v[i+1];
ans[++k]={i, i+1};
}
for(int i=f1-1;i>=l;i--)
{
v[i]^=v[i+1];
ans[++k]={i, i+1};
}
//make all (0, 1) after first (1, 1) and transport (1, 1) to r
int fn0=l-1;
for(int i=f1;i<r;i++)
{
if(fn0==l-1)
fn0=i;
v[i]^=v[i+1];
ans[++k]={i, i+1};
if((v[i+1]&(1<<b))==0)
{
v[i+1]^=v[i];
ans[++k]={i+1, i};
}
else if(i>l && (v[i-1]&(1<<b))>0)
{
v[i]^=v[i-1];
ans[++k]={i, i-1};
}
else
fn0=l-1;
}
for(int i=fn0-1;i>=l;i--)
{
v[i]^=v[i+1];
ans[++k]={i, i+1};
}
//make second half (1, 1)
int mid=(l+r)/2;
for(int i=r-1;i>mid;i--)
{
v[i]^=v[i+1];
ans[++k]={i, i+1};
v[i]^=v[i-1];
ans[++k]={i, i-1};
}
//make first half (1, 0)
for(int i=l;i<mid;i++)
{
v[i]^=v[i+1];
ans[++k]={i, i+1};
}
for(int i=mid;i>=l;i--)
{
v[i]^=v[i+1];
ans[++k]={i, i+1};
}
//solve for each half
solve2(l, mid, b-1);
solve2(mid+1, r, b-1);
}
void afis()
{
cout<<k<<'\n';
for(int i=1;i<=k;i++)
cout<<ans[i].i<<" "<<ans[i].j<<'\n';
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int s;
cin>>n>>s;
for(int i=1;i<=n;i++)
cin>>v[i];
if(s==1)
solve1();
else
solve2(1, n, 19);
afis();
return 0;
}
