import strutils, math


proc nextString: string =
    result = ""
    while not endOfFile stdin:
        let nextChar = readChar stdin
        case nextChar
        of '\r':
            discard
        of "\n"[0], ' ':
            break
        else:
            add result, nextChar


proc main: void =
    let r, d = parseFloat nextString()
    writeLine stdout, pow((d ^ 2 - r ^ 2), 0.5)


when isMainModule:
    main()