def fnc(d,n=0):
    if "".join(map(str,d)) == "".join(map(str,sorted(d))):
        print(n)
    else:
        x = d[0]-1
        if d[0] == min(d):
            x = max(d)-1
        d.remove(x)
        d.insert(0,x)
        fnc(d, n+1)
input()
fnc(list(map(int,input().split(" "))))