# include <iostream>
# include <vector>

using namespace std;

int main()
{
    int n, m, i;
    vector<vector<int>> ans;

    cin >> n >> m;
    int hi[m];
    for(i=0; i<m; i++) {
        cin >> hi[i];
    }

    int rd = 0, rf = 0, fs;
    bool ren = false;
    for (i=0; i<m-1; i++) {

        if (hi[i] + 1 == hi[i+1]) {
            if (ren == false) {
                rd += 1;
                fs = hi[i];
                ren = true;
            }
            rf += 1;
        } 
        else {
            if (ren == true) { 
                rf += 1;
                ans.push_back({fs, rf});
                rf = 0;
            }
            ren = false;
        }
    }

    if (ren == true) {
        rf += 1;
        ans.push_back({fs, rf});
    }
    else{
        rd += 1;
        ans.push_back({n, 1});
    }

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

    return 0;
}