/*
[templates]: 
duipai
spjdp
compre
addhis
floor_sum
treedfs
matrix
network_flow
polynomial
lca
bitset
valuesgt
fenwick
erbitree
*/
//#pragma GCC optimize("Ofast")
//#pragma GCC target("avx")
#include<bits/stdc++.h>
using namespace std;
#define int long long
//use ll instead of int.
#define f(i, a, b) for(int i = (a); i <= (b); i++)
#define cl(i, n) i.clear(),i.resize(n);
#define endl '\n'
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int inf = 1e18;
//#define cerr if(false)cerr
//#define freopen if(false)freopen
mt19937 rng(time(0)); 
int rnd(int l, int r) {return rng() % (r-l+1) + l; }
#define watch(x) cerr  << (#x) << ' '<<'i'<<'s'<<' ' << x << endl
void pofe(int number, int bitnum) {
    string s; f(i, 0, bitnum) {s += char(number & 1) + '0'; number >>= 1; } 
    reverse(s.begin(), s.end()); cerr << s << endl; 
    return;
}
template <typename TYP> void cmax(TYP &x, TYP y) {if(x < y) x = y;}
template <typename TYP> void cmin(TYP &x, TYP y) {if(x > y) x = y;}
//调不出来给我对拍！
//use std::array.
vector<int> vec; 
int deg[20020];
void solve() {
    sort(vec.begin(), vec.end(), greater<int>()); 
    cout << vec.size() << endl; 
    int cnt = 0, cur = 1; 
    for(int i : vec) {
        cnt ++; 
        int tmp = i - deg[cnt]; 
        f(j, 1, tmp) {
            deg[cnt] ++; 
            deg[cur + 1] ++; 
            cout << cnt << " " << cur + 1 << endl; 
            cur ++; 
        }
    }
}
signed main() {
    ios::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);
    //freopen();
    //freopen();
    //time_t start = clock();
    //think twice,code once.
    //think once,debug forever.
    int a, b; cin >> a >> b; 
    if(a == 0 && b == 0) {
        cout << 1 << endl;  
        return 0; 
    }
    else if((a + b) % 2 == 0) {
        if(a - 2 < b) {
            cout << 0 << endl; 
            return 0; 
        }
        else {
            int c = (a - 2 - b) / 2;
            f(i, 1, a) vec.push_back(1); 
            f(i, 1, b) vec.push_back(3); 
            f(i, 1, c) vec.push_back(4); 
            solve(); 
        }
    }
    else {
        if(a - 5 < b) {
            cout << 0 << endl; 
            return 0; 
        }
        else {
            int c = (a - 5 - b) / 2;
            vec.push_back(5); 
            f(i, 1, a) vec.push_back(1); 
            f(i, 1, b) vec.push_back(3); 
            f(i, 1, c) vec.push_back(4); 
            solve(); 
        }
    }
    //time_t finish = clock();
    //cout << "time used:" << (finish-start) * 1.0 / CLOCKS_PER_SEC <<"s"<< endl;
    return 0;
}