#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
using ll = long long;
using P = pair<int, int>;

int main(void){
  int x, y; cin >> x >> y;
  vector<P> ans;
  int c=x+1;
  for(int i=1; i<=x; i++){
    int pre=i;
    for(int j=0; j<y; j++){
      ans.emplace_back(pre, c);
      pre=c, c++;
    }
  }
  cout << c-1 << endl;
  for(auto [u, v]:ans) cout << u << ' ' << v << endl;
  return 0; 
}