#include<iostream>
using namespace std;
int main()
{
int size=0;
int*x;
int max=0;
int value;
x=new int [size];
for(int i=0;i<size;i++){
      x[i]=0;
      }
cout<<"Enter the grade of student"<<endl;
do{
    cin>>value;
    if(value>max)
        max=value;
    if(value>=0)
        x[value]++'
        }while(value !=-1);
        for(int j=0;j<=max;j++)
           cout<<j<<x[j]<<endl;

}