#include <iostream>

using namespace std;

int m=0,i=1,n,u,x;

int main()
{
    cin>>n;
    while(i<=n)
    {
        cin>>x;
        i++;
        while(x>0)
        {
            u=x%10;
            x=x/10;
            if(u>m)
                m=u;
        }
    }
    cout<<m+1;
}