123
include <bits/stdc++.h>
using namespace std; string a; int s=0; int main(){
cin>>a;
for(int i=0;i<a.size();i++){
if(a[i]=='I'){
s++;
}else{
s--;
}
if(s<0){
cout<<"NO"<<endl;
break;
}
}
if(s>=0) {
cout<<"YES"<<endl;
}
return 0;
}