#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("bac.txt");

int F[101],n,gasit;

int main()
{
    while(fin>>n)
        F[n]=1;
    for(int i=0;i<=100;i++)
        if(F[i]==0)
        {
            int j=i;
            while(F[j]==0 && j<=100)
                j++;
            if(i-1!=0 && j!=101)
            {
                cout<<i-1<<" "<<j<<endl;
                gasit=1;
            }
            i=j;
        }
    if(!gasit) cout<<"nu exista";
    return 0;
}