#include <iostream>
#include <algorithm>

using namespace std;

void output(int a,int b,bool flipped){
  if (flipped) swap(a,b);
  printf("%d:%d\n",a,b);
}

int main(){
    int n,a,b;
    cin >> n >> a >> b;
    if (n == 1){
        if (a == b){
            printf("1\n%d:%d\n",a,b);
        }
        else{
          printf("0\n%d:%d\n",a,b);
        }
        return 0;
    }
    int zeros = max(n-(a+b),0);
    cout << zeros << endl;
    for (int i = 1;i <= zeros;i++){
        cout << "0:0\n";
    }
    if (a == 0 && b == 0){
        return 0;
    }
    bool flipped = false;
    if (a == 0){
        swap(a,b);
        flipped = true;
    }
    if (b == 0){
        //use n - zeros to break up all of a
        for (int i = 1;i < n-zeros;i++){
            output(1,0,flipped);
        }
        output(a-(n-zeros-1),0,flipped);
        return 0;
    }
    // use min(a,n -zeros - 1) to break up all of a
    int lft = n - zeros;
    int useda = 0;
    for (int i = 1;i < min(n-zeros-1,a);i++){
        output(1,0,flipped);
        lft--;
        useda++;
    }
    if (a > useda){
      output(a-useda,0,flipped);
      lft--;
    }
    for (int i = 1 ;i < lft;i++){
        output(0,1,flipped);
    }
    if (b > (lft - 1)) output(0,b - (lft - 1),flipped);
}