How do I count the number of elements that appear in every row in a square matrix

ex: n=3
1 2 3
2 3 4
3 4 5
The answer is 1 because only number 3 appear in every row

#include <iostream>

using namespace std;

void input(int **a,int n)
{
    for(int i=0; i<n; i++)
    {
        for(int j=0; j<n; j++)
            cin>>a[i][j];
    }
}

void output(int **a,int n)
{
    int result=0;
    for(int i=1; i<n; i++)
    {
        bool appear=false;
        for(int j=0; j<n; j++)
        {
            for(int k=0; k<n; k++)
            {
                if(a[i][j]==a[0][k])
                {
                    appear=true;
                    break;
                }
            }
        }
        if(appear)
            result++;
    }
    cout<<result<<endl;
}

int main()
{
    int t, n;
    cin>>t;
    while(t--)
    {
        cin>>n;
        int **a=new int*[n];
        for(int i=0; i<n; i++)
            a[i]=new int[n];
        input(a,n);
        output(a,n);
    }
    return 0;
}