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

using ll = long long;

bool chmin(auto &a, auto b) { return a > b ? a = b, true : false; }
bool chmax(auto &a, auto b) { return a < b ? a = b, true : false; }

template<typename T>
vector<pair<T, int>> run_length_encoding(const vector<T> &v) {
    vector<pair<T, int>> res;
    for (const auto &x : v) {
        if (res.empty() || res.back().first != x) {
            res.emplace_back(x, 0);
        }
        res.back().second++;
    }
    return res;
}

vector<pair<char, int>> run_length_encoding(const string &s) {
    return run_length_encoding(vector<char>(s.begin(), s.end()));
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int N, M;
    cin >> N >> M;
    vector<int> A(M);
    for (int i = 0; i < M; i++) cin >> A[i], A[i] -= i;
    auto P = run_length_encoding(A);
    cout << P.size() << '\n';
    int k = 0;
    for (auto [a, l] : P) {
        cout << a + k << ' ' << l << '\n';
        k += l;
    }
}