#include <bits/stdc++.h>
using namespace std;
int main()
{
    int N, M;
    cin >> N >> M;
    vector<int> A(M);
    for (int i = 0; i < M; ++i)
        cin >> A[i];
    vector<pair<int, int>> ans;
    int now = 0;
    for (int i = 1; i < M; ++i)
    {
        if (A[i - 1] + 1 != A[i])
        {
            ans.emplace_back(A[now], i - now);
            now = i;
        }
    }
    ans.emplace_back(A[now], M - now);
    cout << ans.size() << endl;
    for (auto x : ans)
        cout << x.first << " " << x.second << endl;
    return 0;
}