function Main(input) {

    let src = input.split("\n");
    let d = parseInt(src[0]);
    let arr = src[1].split(" ");
    let a = parseInt(arr[0]);
    let b = parseInt(arr[1]);
    let ans = 100000000;

    for (let x = 0; x <= d; x++) {
        ans = Math.min(ans, x * a + (d - x) * b);
    }
    console.log(ans);
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));