#include <bits/stdc++.h>
using namespace std;
int main() {
  int A, B, ans = 1;
  cin >> A >> B;
  string S;
  cin >> S;
  for (int i = 0; i < A + B + 1; i++) {
    if (i == A) continue;
    if (!('0' <= S[i] && S[i] <= '9')) ans = 0;
  }
  if (ans)
    printf("Yes");
  else
    printf("No");
  return 0;
}
