#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vs = vector<string>;
#define endl ('\n')
inline vector<int64_t> range(int64_t stop){vector<int64_t>v(stop);iota(v.begin(),v.end(),0LL);return v;}
inline vector<int64_t> range(int64_t start,int64_t stop){vector<int64_t>v(stop-start);iota(v.begin(),v.end(),start);return v;}
inline vector<int64_t> range(int64_t start,int64_t stop,int64_t step){int s=step>0?(stop-start+step-1)/step:(stop-start+step+1)/step;if(s<=0)return {};vector<int64_t>v(s);for(int i=0;i<s;++i)v[i]=i?v[i-1]+step:start;return v;}


int main(){
    int n, k;
    cin >> n >> k;
    int mx, mn;
    mx = 0;
    mn = 1e5;
    for(auto i:range(k)){
        int a;
        cin >> a;
        mx = max(mx, a);
        mn = min(mn, a);
    }
    cout << mx - mn << endl;
    return 0;
}