#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, i, n, flag = 0;
  cin >> a >> b;
  char x[a + b + 1];
  n = strlen(x);
  for (i = 0; i < n; i++) {
    cin >> x[i];
  }
  for (i = 0; i < n; i++) {
    if ((i != a) && (x[i] >= '0') && (x[i] <= '9'))
      flag = 0;
    else {
      cout << "No" << endl;
      flag = 1;
      break;
    }
  }
  if (flag == 0) cout << "Yes" << endl;
}
