#include <iostream>
#include <vector>

using namespace std;

int main()
{
    int v_base, v_cut, tp, fst = 0;
    int i, flen = 1;
    bool flg = false;
    vector<int> v_f;
    vector<vector<int>> ans;

    cin >> v_base >> v_cut;

    for (i=0; i<v_cut; i++) {
        cin >> tp;
        v_f.push_back(tp);

        if (i == 0) continue;

        if (v_f[fst] + flen == v_f[i]) {
            if (! flg) fst = i - 1;
            flen += 1;
            flg = true;
            if (i == v_cut - 1) ans.push_back({v_f[fst], flen});
           
        }
        else {
            if (flg) ans.push_back({v_f[fst], flen});
            flen = 1, fst = i;
            flg = false;
        }

    }

    if (ans.empty()) {
        cout << v_cut << endl;

        for (auto it=v_f.begin(); it<v_f.end(); it++) {
            cout << *it << " 1" << endl;
        }
    }
    else {
        if (! flg) ans.push_back({v_f[v_cut-1], 1});
        cout << ans.size() << endl;

        for (i=0; i<ans.size(); i++) {
            cout << ans[i][0] << " " << ans[i][1] << endl;
        }
    }

    return 0;
}