var
n, a, b, c, d: real;
begin
try
assign(input, 'input.txt');
assign(output, 'output.txt');
reset(input);
rewrite(output);
read(input, n, a, b, c, d);
write(output, trunc(a * b * 2 * n * c / d) + 1);
finally
try
close(input);
close(output);
except
end;
end;
end.