import std.stdio, std.string, std.conv;
import std.algorithm, std.array;
import core.stdc.stdlib;

void main(){
    auto s = readln.strip.to!int;
    int[] arr = readln.strip.split.map!(to!int).array;
    if(s == 1){0.writeln;exit(-1);}
    arr.sort;
    int ans, before;
    ans = arr[1] - arr[0];
    foreach(i, x; arr){
        if(before == x || i == 0) continue;
        if(ans > x - before){
            ans = x - before;
        }
        before = x;
    }
    writeln(ans);
}