import 'dart:io';
 
void main(List<String> args) {
  List<int> x = stdin.readLineSync().split(" ").map((i) => int.parse(i)).toList();
  String N = stdin.readLineSync();
  String ans = "Yes";
  for(int i=0; i<x[0]+x[1]+1; ++i){
    if(i==x[0]){
    	if(N[i]!='-') ans = "No";
    }else{
    	if(N[i]=='i') ans = "No";
    }
  }
  print(ans);
}