#include <bits/stdc++.h>
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int N; cin >> N;
    if(N == 1){cout << 0 << endl; return 0;}
    vector<int>  ap(1001001);
    while(N--){
        int x; cin >> x;
        ap.at(x)++;
    }
    int back = -1001001,answer = 10010001;
    for(int i=0; i<=1000000; i++){
        if(ap.at(i) > 1){answer = 0; break;}
        if(ap.at(i) == 1) answer = min(answer,i-back),back = i;
    }
    cout << answer << endl;
}