#include <iostream>
#include <fstream>
using namespace std;
ifstream in ("cifre.in");
ofstream out ("cifre.out");
long a[11],b[11],n,i,x,y,j,k,p,cod,cate,maxim,minim;
int main()
{in>>p>>n;

for(i=1;i<=n;i++)
{
    in>>x>>y;
    for(j=0;j<10;j++)
        a[j]=b[j]=0;
    while(x)
    {a[x%10]++;
    x=x/10;
    }
    while(y)
     {b[y%10]++;
    y=y/10;}
    cod=0;
    for(j=9;j>=0;j--)
        if(a[j]>0 && b[j]>0)
        {if(a[j]<b[j])
        minim=a[j];
        else
        minim=b[j];
         for(k=1;k<=minim;k++)
            cod=cod*10+j;


}//cout<<cod;
if(cod)
cate++;
 if(cod>maxim)
 maxim=cod;
}
if(p==1)
    out <<cate << endl;
    else
     out<<maxim;
    return 0;
}