DSA02035 - HOÁN VỊ CÁC CHỮ SỐ

//Made By Phuong Nam PROPTIT <3//
#pragma GCC Optimize("O3")
#include<bits/stdc++.h>
#include<string>
#include<vector>
#define alphaa "abcdefghijklmnopqrstuvwxyz"
#define ALPHAA "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
#define f(i,a,b) for(int i=a;i<=b;i++)
#define f1(i,n) for(int i=1;i<=n;i++)
#define f0(i,n) for(int i=0;i<n;i++)
#define ff(i,b,a) for(int i=b;i>=a;i--)
#define el cout<<'\n'
#define fi first
#define se second
#define eb emplace_back
#define pk pop_back
#define vi vector<int>
#define vl vector<ll>
#define pii pair<int,int>
#define pll pair<ll,ll>
#define all(s) s.begin(),s.end()
using namespace std;
typedef long long ll;
const int N=1e6+3;
const int MOD=1e9+7;
template<class X,class Y>
    void minimize(X &x,const Y &y) {
        if (x>y) x=y;
    }
template<class X,class Y>
    void maximize(X &x,const Y &y) {
        if (x<y) x=y;
    }
template<class T>
    T Abs(const T &x) {
        return (x<0?-x:x);
    }
int n,k,c[10],ans=1e9;
string a[10];
void xuly()
{
    cin>>n>>k;
    f1(i,n) cin>>a[i];
    f0(i,k) c[i]=i;
    do
    {
        int ma=0,mi=1e9;
        f1(i,n)
        {
            int t=0;
            f0(j,a[i].size()) t=t*10+(a[i][c[j]]-'0');
            ma=max(ma,t);
            mi=min(mi,t);
        }
        //cout<<ma<<' '<<mi<<'\n';
        ans=min(ans,ma-mi);
    }while(next_permutation(c,c+k));
    cout<<ans;
}
int main()
{
  ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
  int t=1;
  //cin>>t;
  while(t--) xuly();
  return 0;
}
//-----YEU CODE HON CRUSH-----//