#include <iostream>
#include <fstream>

int main(int argc, char const *argv[])
{
  std::ifstream inputFile(argv[1]);

  int boxSize, goldSize, goldValue, silverSize, silverValue;

  while (inputFile >> boxSize >> goldSize >> goldValue >> silverSize >> silverValue)
  {
    int maxValue = 0;
    int goldCount = boxSize / goldSize;
    int silverCount = boxSize / silverSize;

    for (size_t i = 0; i <= goldCount; i++)
    {
      for (size_t j = 0; j <= silverCount; j++)
      {
        if (i * goldSize + j * silverSize <= boxSize)
        {
          int value = i * goldValue + j * silverValue;
          maxValue = std::max(maxValue, value);
        }
      }
    }
    printf("%d\n", maxValue);
  }
  inputFile.close();
  return 0;
}