#include <bits/stdc++.h>
using namespace std;
int main() {
  string A, B, S;
  cin >> A >> B;
  cin >> S;
  if (stoi(S) != stoi(A) + stoi(B) + 1) {
    cout << "No" << endl;
  } else {
    if (S[stoi(A)] == '-') {
      cout << "Yes" << endl;
    } else {
      cout << "No" << endl;
    }
  }
  return 0;
}
