import std;

alias sread = () => readln.chomp();
alias lread = () => readln.chomp.to!long();
alias aryread(T = long) = () => readln.split.to!(T[]);
//aryread!string();
//auto PS = new Tuple!(long,string)[](M);
//x[]=1;でlong[]全要素1に初期化
void main()
{
    auto n = lread();
    auto a = aryread();
    // writeln(a);
    auto ans = new long[](n);
    foreach (i; 0 .. (n - 1))
    {
        if (a[i] == a[i + 1])
        {
            ans[i + 1] = 0;
        }
        else if (a[i] > a[i + 1])
        {
            ans[i + 1] = a[i] - a[i + 1];
            a[i + 1] = a[i];
        }
    }
    // writeln(ans);
    sum(ans).writeln();
}

void scan(L...)(ref L A)
{
    auto l = readln.split;
    foreach (i, T; L)
    {
        A[i] = l[i].to!T;
    }
}

void arywrite(T)(T a)
{
    a.map!text.join(' ').writeln;
}
