def find(s):
    k = []
    for i in range(len(s)):
        for j in range(len(s)):
            if(i!=j):
                k.append([abs(s[i]-s[j]),s[i],s[j],(s[i]+s[j])/2])
    #print(k)
    f = min(k)
    return f
    
n = int(input())
s = list(map(int,input().split()))
while(len(s)!=1):
    cur = find(s)
    #print(s)
    s = [i for i in s if i!=cur[1] and i!=cur[2]]
    s.append(cur[3])
print(s[0])    
    
            