CSMAX C++

#include <bits/stdc++.h>
using namespace std;
int x,n,maxx;
int main ()
{
    freopen("csmax.inp","r",stdin);
    freopen("csmax.out","w",stdout);
    cin>>n;
    maxx=0;
    while(n>0)
    {
        x=n%10;
        if(x>maxx) maxx=x;
        n=n/10;
    }
    cout<<maxx;
}