#include<bits/stdc++.h>
using namespace std;

int main()
{
    int a , b;
    cin>>a>>b;
    string str;
    cin>>str;
    bool flag = true;
    if(str[a]!='-')
    flag = false;
    for(int i = 0; i < str.size(); i++)
    {
        if(a==i) continue;
        if(str[i]=='-') flag = false;
    }
    if(flag)
    cout<<"YES"<<endl;
    else
    cout<<"NO"<<endl;
 return 0;
}
