#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int input[] = {5,1,8,6,9,2,44,3,31,26,36,47,51,72,88,7,4};
int N=sizeof(input)/sizeof(int);
int K = 10; 
void print_pair(int *input,int K) {
        int *mem=alloca(sizeof(int)*K);
        int t,i;
        memset(mem,0,sizeof(int)*K);
        for(t=0;t<N;t++) {
                i=input[t];
                if (i<=0 || i>=K) continue;
                if (mem[K-i]!=0) {
                        printf("%d %d\n",i,K-i);
                        mem[K-i]=0;
                } else
                        mem[i]=1;
        }   
}
int main() {
        print_pair(input,K);
        return 0;
}