import std.algorithm, std.container, std.conv, std.math, std.range, std.typecons, std.stdio, std.string;

auto rdsp(){return readln.splitter;}
void pick(R,T)(ref R r,ref T t){t=r.front.to!T;r.popFront;}
void readV(T...)(ref T t){auto r=rdsp;foreach(ref v;t)pick(r,v);}

void main()
{
  int a, b, t; readV(a, b, t);

  auto r = int.max;
  foreach (y; 0..min(a, (t+b-1)/b)+1) {
    auto s = t-b*y;
    if (s == 0)
      r = min(r, b*y);
    else
      r = min(r, y*b + (s+a-1)/a*a);
  }

  writeln(r);
}