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

template <class T> using V = vector<T>;

using ll = long long;
using db = double;
using st = string;
using ch = char;
using vll = V<ll>;
using vpll =V<pair<ll,ll>>;
using vst = V<st>;
using vdb = V<db>;
using vch = V<ch>;


#define FOR(i,a,b) for(ll i=(a);i<(ll)(b);i++)
#define rFOR(i,a,b) for(ll i=(b);i>(ll)(a);i--)
#define oFOR(i,a,b) for(ll i=(a);i<(ll)(b);i+=2)
#define bgn begin()
#define en end()
#define SORT(a) sort((a).bgn,(a).en)
#define REV(a) reverse((a).bgn,(a).en)
#define M(a,b) max(a,b)
#define rM(a,b) min(a,b)
#define fi first
#define se second
#define sz size()
#define gcd(a,b) __gcd(a,b)
#define lcm(a,b) __lcm(a,b)
#define co(a) cout<<a<<endl;
#define ci(a) cin>>a;



int main() {
  ll a,b;
  	ci(a>>b);
  st s;
  	ci(s);
  ch now;
  ll count=0;
  FOR(i,0,b+1){
    now=s[i];
    if(i==a){
      if(now!='-'){
        co("No")
          break;
      }
    }
      else{
        if(now<'0'||'9'<now){
          co("No")
            break;
        }
      }
        count++;
      }
  
  if(count==b+1){
    co("Yes")
  }      