#include <bits/stdc++.h>
using namespace std;
#define MAX_N (int)2e5+20
#define INF 2e9+20
#define pb push_back
#define F first
#define S second
typedef long long LL;
#define int LL
typedef pair<int,int> pii;
const int delta=(int)1e9+7;
int a,b; string s;
main(){
	ios_base::sync_with_stdio(false); cin.tie(0);
        cin>>a>>b>>s;
        for(int i=0;i<s.size();++i){
              if((i!=a && (s[i]<'0' || s[i] >'9')) || (i==a && s[i]!='-'))	return cout<<"No\n",0;
        }
	cout<<"Yes";
	return cout<<endl;
}