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()
{
    long n, x, t;
    scan(n, x, t);
    // writeln(n, x, t);
    long cnt;
    long time;
    foreach (_; 0 .. 10 ^^ 7)
    {
        cnt += x;
        time += t;
        // writeln(cnt);
        if (cnt >= n)
        {
            writeln(time);
            return;
        }
    }
}

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;
}
