#include<stdio.h>
int main() {
    int n;
    int left[50001],right[50001];
    int i,j,temp,begin,end;
    scanf("%d",&n);
    for (i=1;i<=n;i++) scanf("%d%d",&left[i],&right[i]);
    for (i=1;i<n;i++)
        for (j=i+1;j<=n;j++)
            if (left[i]>left[j]||(left[i]==left[j] && right[i]>right[j])) {
               temp=left[i];
               left[i]=left[j];
               left[j]=temp;
               
               temp=right[i];
               right[i]=right[j];
               right[j]=temp;
               }            
    begin=left[1];
    end=right[1];
    for (i=2;i<=n;i++){
        if (left[i]<=end) end=right[i];
        else {
             printf("%d %d\n",begin,end);
             begin=left[i];
             end=right[i];
             }
        }
    printf("%d %d\n",begin,end);     
    scanf("%d",&n);       
    return 0;
}