//#define _GLIBCXX_DEBUG

#include<bits/stdc++.h>
#define PI 3.14159265359
using namespace std;
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
const int INF= 1e9+5;
typedef long long ll;
typedef vector<ll> vl;
typedef vector<vector<ll> >vvl;
typedef pair<ll,ll> P;
typedef tuple<ll,ll,ll> T;
const ll MOD=1000000007LL;
string abc="abcdefghijklmnopqrstuvwxyz";
string ABC="ABCDEFGHIJKLMNOPQRSTUVWXYZ";

int main(){
  ll a,b;cin>>a>>b;
  string s;cin>>s;
  if(s[i]!='-'){
    cout<<"No"<<endl;
    return 0;
  }
  ll count=0;
  rep(i,s.size()){
    if(s[i]!='-')count++;
  }
  if(count==a+b){
    cout<<"Yes"<<endl;
    return 0;
  }
  cout<<"No"<<endl;
}