#include <bits/stdc++.h>
using namespace std;

void solve1(int n, vector<int>&a)
{
    vector<pair<int, int>>ans;
    vector<pair<int, int>>b(n);
    vector<int>pos(n);
    for(int i = 0; i < n; i++) b[i] = {a[i], i};
    sort(b.rbegin(), b.rend());
    for(int i = 0; i < n; i++)
    {
        int cnt = 0;
        for(int j = 0; j < i; j++) if(b[j].second < b[i].second) cnt++;
        pos[i] = b[i].second - cnt;
    }
    for(int i = 0; i < n; i++)
    {
        int last = n-i-1;
        int k = pos[i];
        for(int j = 0; j < last; j++)
        {
            a[j] ^= a[j+1];
            ans.push_back({j+1, j+2});
        }
        for(int j = k-2; j >= 0; j--)
        {
            a[j] ^= a[j+1];
            ans.push_back({j+1, j+2});
        }
        for(int j = k+1; j <= last; j++)
        {
            a[j] ^= a[j-1];
            ans.push_back({j+1, j});
        }
    }
    for(int i = n-2; i >= 0; i--)
    {
        a[i] ^= a[i+1];
        ans.push_back({i+1, i+2});
    }
    cout << (int)ans.size() << '\n';
    for(auto [l, r] : ans) cout << l << " " << r << '\n';
}

void solve2(int n, vector<int>&a)
{
    vector<pair<int, int>>ans;
    int cnt = n;
    for(int k = 19; k >= 0; k--)
    {
        bool ok = 0;
        for(int u : a) if((u >> k) & 1) ok = 1;
        if(!ok) continue;
        cnt--;
        for(int i = 0; i < cnt; i++)
        {
            if((a[i] >> k) & 1)
            {
                if((a[i+1] >> k) & 1)
                {
                    a[i] ^= a[i+1];
                    ans.push_back({i+1, i+2});
                }
                else
                {
                    a[i+1] ^= a[i];
                    a[i] ^= a[i+1];
                    ans.push_back({i+2, i+1});
                    ans.push_back({i+1, i+2});
                }
            }
        }
    }
    cout << (int)ans.size() << '\n';
    for(auto [l, r] : ans) cout << l << " " << r << '\n';
}

signed main() {
    ios::sync_with_stdio(false);cin.tie(nullptr);
	int n, s; cin >> n >> s;
    vector<int>a(n);
    for(int &i : a) cin >> i;
    if(s == 1) solve1(n, a);
    else solve2(n, a);
}