#include <bits/stdc++.h>
using namespace std;
#define m_p make_pair
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define fi first
#define se second
typedef long long ll;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
mt19937 rnf(2106);
const int N = 1003, m = 20;
int n, ty;
int a[N];
vector<pair<int, int> > ans;
void ubd(int x, int y)
{
ans.push_back(m_p(x, y));
a[x] ^= a[y];
}
void solv2()
{
int nn = n;
for (int j = m - 1; j >= 0; --j)
{
for (int i = 1; i < nn; ++i)
{
if ((a[i] & (1 << j)))
{
if ((a[i + 1] & (1 << j)))
ubd(i, i + 1);
else
{
ubd(i + 1, i);
ubd(i, i + 1);
}
}
}
if ((a[nn] & (1 << j)))
--nn;
}
for (int i = 1; i < n; ++i)
assert(a[i] <= a[i + 1]);
cout << sz(ans) << "\n";
for (int i = 0; i < sz(ans); ++i)
cout << ans[i].fi << ' ' << ans[i].se << "\n";
}
void solv()
{
cin >> n >> ty;
for (int i = 1; i <= n; ++i)
cin >> a[i];
if (ty == 2)
{
solv2();
return;
}
}
int main()
{
#ifdef SOMETHING
freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);
#endif // SOMETHING
ios_base::sync_with_stdio(false), cin.tie(0);
int tt = 1;
//cin >> tt;
while (tt--)
{
solv();
}
return 0;
}
