void main(){
  import std.stdio, std.string, std.conv, std.algorithm;

  int n; rd(n);
  int c, v; rd(c, v);

  auto rec=new int[](3*n);
  fill(rec, 1_000_000_000);
  rec[0]=rec[1]=0;
  foreach(i; 1..n)for(int j=1; i*(1+j)<=n*2; j++){
    chmin(rec[i*(1+j)], rec[i]+c+v*j);
  }

  writeln(reduce!(min)(rec[n..(2*n+1)]));
}

void chmin(T)(ref T x, T y){
  if(x>y) x=y;
}

void rd(T...)(ref T x){
  import std.stdio, std.string, std.conv;
  auto l=readln.split;
  assert(l.length==x.length);
  foreach(i, ref e; x){
    e=l[i].to!(typeof(e));
  }
}