// https://atcoder.jp/contests/abc158/tasks/abc158_a
function main(s) {
    var ans;
    for (var ch = s[0], i = 1; i < 3; i++) {
         if (ch !== s[i]) {
               ans = 1;
               break;
         }
    }
    console.log(ans? "Yes": "No");
}
main(require("fs").readFileSync("/dev/stdin", "utf8"));
