C :

#include<stdio.h>
#include<malloc.h>
typedef struct student
{
    int a;
    int b;
    struct student *next;
} STU;
int main()
{
    int m,n;
    scanf("%d%d",&n,&m);
    int i,j,k,l;
    i=n;
    j=m;
    STU *q1,*q2,head1,head2,*p;
       q1=&head1;
       q2=&head2;
    while(i--)
    {
        p=(STU*)malloc(sizeof(STU));
        scanf("%d %d",&p->a,&p->b);
        q1->next=p;
        q1=q1->next;
    }
        while(j--)
    {
        p=(STU*)malloc(sizeof(STU));
        scanf("%d %d",&p->a,&p->b);
        q2->next=p;
        q2=q2->next;
    }
    q1->next=head2.next;
    STU *x,*y;
    for(x=head1.next; x!=NULL;x=x->next)
        for(y=x; y!=NULL;y=y->next)
        if(x->a>y->a)
    {
        int temp;
        temp=x->a;
        x->a=y->a;
        y->a=temp;
         temp=x->b;
        x->b=y->b;
        y->b=temp;
    }
    STU *g;
    g=head1.next;
    while(g!=NULL)
    {
        printf("%d ",g->a);
        printf("%d\n",g->b);
        g=g->next;
    }
    return 0;
}

C++ :

#include <iostream>
#include<algorithm>
#include<cmath>
using namespace std;
struct A
{
    int num,score;
}a[100000];
int cmp(A p1,A p2)
{

    if(p1.num<p2.num) return 1;
    else return 0;
}
int main()
{
    int N,M,i,j,k;
    cin>>N>>M;
    for(i = 0,j = 0;i < N; i++,j++)
    cin>>a[j].num>>a[j].score;
    for(k = 0;k < M;k++,j++)
    cin>>a[j].num>>a[j].score;
    sort(a,a+N+M,cmp);
    for(i = 0;i < N + M; i++)
    cout<<a[i].num<<" "<<a[i].score<<endl;
   
    return 0;
}