import std.stdio,std.string,std.conv,std.algorithm;
import std.algorithm:rev=reverse;

int main(){
    auto s=readln.chomp.dup;
    foreach(t;s[1..3]){
        if(t!=s[0]){
            writeln("Yes");
            return 0;
        }
    }   
    writeln("No");
    return 0;
}