// Optimized using Hahsh map
// TC: O(n) 
// SC: O(n)

function minimumDistances(a) {
    let hash = {}; // number to its first index 
    let minDist = Infinity; 
    
    for(let i = 0; i < a.length; i++) {
        if(hash[a[i]] !== undefined) {
            minDist = Math.min(minDist, Math.abs(i - hash[a[i]])); 
        }
        else {
            hash[a[i]] = i; 
        }
    }
    
    if(minDist === Infinity) {
        return -1;
    }
    
    return minDist; 
}

int minimumDistances(vector<int> a) {
    map<int, int>mp;
    int result = 1000;
    for(int i = 0; i < a.size(); i++){
        if(mp[a[i]]){
            result = min(result, i + 1 - mp[a[i]]);
        }
        mp[a[i]] = i+1;
    }
    return (result == 1000) ? -1:result;
}

 unordered_map<int, pair<int,int>> NumberToIdx;
    int MinDist = INT_MAX;

    for(int i = 0 ; i < a.size(); ++i){
        
        if(NumberToIdx.find(a[i]) == NumberToIdx.end()){
            NumberToIdx[a[i]] = make_pair(i,INT_MAX);
        }
        else{
            if(NumberToIdx[a[i]].second == INT_MAX){
                NumberToIdx[a[i]].second = i;
                MinDist = min(MinDist , (NumberToIdx[a[i]].second - NumberToIdx[a[i]].first));
            }

            else{
                int d = i - NumberToIdx[a[i]].second; 
                MinDist = min(MinDist , d);
            }
        }
    }

    if(MinDist == INT_MAX)
        return -1;
    
    return MinDist;

def minimumDistances(a):
    dist = float('inf')
    for i in range(len(a)):
        if a[i] in a[i+1:]:
            b = a.index(a[i],i+1,len(a))
            dist = min(dist,abs(i-b))
    if dist == float('inf'):
        return -1 
    else:
        return dist
        

def minimumDistances(a):
    min_d = 10000
    
    for i in range(len(a)-1):
        for j in range(i+1, len(a)):
            if (a[i] == a[j]):
                min_d = min(min_d, abs(i-j))
    
    return -1 if min_d == 10000 else min_d

n = int(input())
a = list(map(int, input().split()))

result = minimumDistances(a)

print(result)