function Main(input) {
    let src = input.replace("\n", "").split(" ");
    let a = parseInt(src[0]);
    let b = parseInt(src[1]);
    let ans = Math.floor(50 * a + (50 * a / (0.8 + 0.2 * b)));
    console.log(ans);
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));