Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"sort"
	"strconv"
)

const (
	initialBufSize = 1e4
	maxBufSize     = 1e6 + 7
)

var buf []byte = make([]byte, maxBufSize)
var sc = bufio.NewScanner(os.Stdin)

func init() {
	sc.Split(bufio.ScanWords)
	sc.Buffer(buf, maxBufSize)
}

func main() {
	for {
		n := nextInt()
		if n == 0 {
			break
		}
		an := make([]int, n)
		min := 1000000
		for i := 0; i < n; i++ {
			an[i] = nextInt()
		}
		sort.Ints(an)
		for i := 1; i < n; i++ {
			sub := an[i] - an[i-1]
			if min > sub {
				min = sub
			}
		}
		fmt.Println(min)
	}
}

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

C++: #include "bits/stdc++.h"

using namespace std;

#define DEBUG(x) cerr<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cerr<<#v<<":";for(int i=0;i<v.size();i++) cerr<<" "<<v[i]; cerr<<endl

typedef long long ll;
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
#define pll pair<ll,ll>
template<class S, class T> pair<S, T> operator+(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first + t.first, s.second + t.second); }
template<class S, class T> pair<S, T> operator-(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first - t.first, s.second - t.second); }
template<class S, class T> ostream& operator<<(ostream& os, pair<S, T> p) { os << "(" << p.first << ", " << p.second << ")"; return os; }
#define X first
#define Y second
#define rep(i,n) for(ll i=0;i<(ll)(n);i++)
#define rep1(i,n) for(ll i=1;i<=(ll)(n);i++)
#define rrep(i,n) for(ll i=(ll)(n)-1;i>=0;i--)
#define rrep1(i,n) for(ll i=(ll)(n);i>0;i--)
#define REP(i,a,b) for(ll i=(ll)a;i<(ll)b;i++)
#define in(x, a, b) (a <= x && x < b)
#define all(c) c.begin(),c.end()
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a = b; return 1; } return 0; }
#define UNIQUE(v) v.erase(std::unique(v.begin(), v.end()), v.end());
const ll inf = 1000000001;
const ll INF = 2e18;
const ll MOD = 1000000007;
const double pi = 3.14159265358979323846;
#define Sp(p) cout<<setprecision(15)<< fixed<<p<<endl;
int dx[4] = { 1,0, -1,0 }, dy[4] = { 0,1,0,-1 };
int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };
#define fio() cin.tie(0); ios::sync_with_stdio(false);


int main() {
  while (true) {
    int n;
    cin >> n;
    if (!n) {
      return 0;
    }
    vi a(n);
    rep (i, n) {
      cin >> a[i];
    }
    sort(all(a));
    int ans = inf;
    rep (i, n - 1) {
      ans = min(ans, a[i + 1] - a[i]);
    }
    cout << ans << endl;
  }
}

C++: #include <iostream>
#include <vector>
using namespace std;

int main (){
    int n;
	while(cin>>n && n){
		vector<int> v(n);
		int ans=0;
		for(int i=0;i<n;i++)cin>>v[i];

		for(int i=0;i<n;i++){
			for(int j=0;j<n;j++){
				if(i!=j)ans=max(ans,abs(v[i]-v[j]));
			}
		}
		cout<<ans<<endl;
	}
}

C++: #include<iostream>
using namespace std;

int main(void){
  int n;
  int a[1000]={};
  int min=1000000;
  cin>>n;
  while(n!=0){
    min=1000000;
    for(int i=0;i<n;i++){
      cin>>a[i];
    }
    for(int i=0;i<n/2;i++){
      for(int j=0;j<n;j++){
	if(i!=j){
	  int sa;
	  if(0>(a[i]-a[j])){
	    sa=a[j]-a[i];
	  }else{
	    sa=a[i]-a[j];
	  }
	  //  cout<<sa<<" "<<min<<endl;
	  if(sa<min)min=sa;
	  //  cout<<sa<<" "<<min<<endl;
	}
      }
    }
    cout<<min<<endl;
    cin>>n;
  }
}

C++: #include<iostream>
#include<cstdlib>
using namespace std;

int main(){
	while(1){
		int n;
		cin>>n;
		if(n==0)
			break;
		int a[1000];
		for(int i=0;i<n;i++){
			cin>>a[i];
		}
		int s=1000001;
		for(int i=0;i<n-1;i++){
			for(int j=i+1;j<n;j++){
				if(s>abs(a[i]-a[j])){
					s=abs(a[i]-a[j]);
				}
			}
		}
		cout<<s<<endl;
	}
	return 0;
}

C++: //#define _GRIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;

// ?????¬???????????¬??????
#pragma region MACRO
#define P(x) cout << (x) << endl
#define p(x) cout << (x)
#define PED cout << "\n"
#define rep(i,n) for(int i=0; i<(int)n; ++i)
#define REP(i,x,n) for(int i=x; i<(int)n; ++i)
#define repi(i,n) for(int i=0; i<=(int)n; ++i)
#define REPI(i,x,n) for(int i=x; i<=(int)n; ++i)
#define ILP while(true)
#define FOR(i,c) for(__typeof((c).begin())!=(c).begin(); i!=(c).end(); ++i)
#define ALL(c) (c).begin(), (c).end()
#define mp make_pair
#pragma endregion

// ???
#pragma region TYPE_DEF
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<string, string> pss;
typedef pair<string, int> psi;
typedef pair<int, string> pis;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<long double> vld;
typedef vector<long> vl;
typedef vector<long long> vll;
typedef vector<string> vs;
#pragma endregion

// Effective std
#pragma region ESTD
template<typename C, typename T> int count(C& c, T t) { return count(ALL(c), t); }
template<typename C, typename F> int count_if(C& c, F f) { return count_if(ALL(c), f); }
template<typename C, typename T> void erase(C& c, T t) { remove(ALL(c), t), c.end(); }
template<typename C> void remove(vector<C>& c, unsigned int index) { c.erase(c.begin()+index); }
template<typename C, typename T, typename U> void replace(C& c, T t, U u) { replace(ALL(c), t, u); }
template<typename C, typename F, typename U> void replace_if(C& c, F f, U u) { (ALL(c), f, u); }
template<typename C> void reverse(C& c) { reverse(ALL(c)); }
template<typename C> void sort(C& c) { sort(ALL(c)); }
template<typename C, typename Pred> void sort(C& c, Pred p) { sort(ALL(c), p); }
#pragma endregion

// ?????°
#pragma region CONST_VAL
constexpr int PI = (2*acos(0.0));
constexpr int EPS = (1e-9);
constexpr int MOD = (int)(1e9+7);
constexpr int INF = 100000000;
#pragma endregion


int main()
{
    int n;
    while(cin>>n, n) {
        vi v(n);
        rep(i,n) cin >> v[i];
        sort(v);
        int ans = INF;
        rep(i,n-1) {
            ans = min(ans, v[i+1]-v[i]);
        }
        P(ans);
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define int long long   // <-----!!!!!!!!!!!!!!!!!!!

#define rep(i,n) for (int i=0;i<(n);i++)
#define rep2(i,a,b) for (int i=(a);i<(b);i++)
#define rrep(i,n) for (int i=(n)-1;i>=0;i--)
#define rrep2(i,a,b) for (int i=(a)-1;i>=b;i--)
#define chmin(a,b) (a)=min((a),(b));
#define chmax(a,b) (a)=max((a),(b));
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
#define printV(v) cout<<(#v)<<":";for(auto(x):(v)){cout<<" "<<(x);}cout<<endl;
#define printVS(vs) cout<<(#vs)<<":"<<endl;for(auto(s):(vs)){cout<<(s)<< endl;}
#define printVV(vv) cout<<(#vv)<<":"<<endl;for(auto(v):(vv)){for(auto(x):(v)){cout<<" "<<(x);}cout<<endl;}
#define printP(p) cout<<(#p)<<(p).first<<" "<<(p).second<<endl;
#define printVP(vp) cout<<(#vp)<<":"<<endl;for(auto(p):(vp)){cout<<(p).first<<" "<<(p).second<<endl;}

inline void output(){ cerr << endl; }
template<typename First, typename... Rest>
inline void output(const First& first, const Rest&... rest) {
    cerr << first << " "; output(rest...);
}

using ll = long long;
using Pii = pair<int, int>;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
const int inf = 2e9;
const int mod = 1e9 + 7;


signed main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);

    int n;
    while (cin >> n, n) {
        vi a(n);
        rep(i, n) cin >> a[i];

        int ans = inf;
        rep(i, n) {
            rep(j, i) {
                chmin(ans, abs(a[i] - a[j]));
            }
        }
        cout << ans << endl;        
    }
}