#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b;
  cin >> a >> b;
  char rem[a + 1];
  char ram[b + 1];
  scanf("%s%s", rem, ram);
  int yes = 1;
  if (ram[0] != '-') yes = 0;
  if (yes == 1) {
    for (int i = 0; i < a; i++) {
      if (rem[i] < '0' || rem[i] > '9') {
        yes = 0;
        break;
      }
    }
    for (int i = 1; i < b; i++) {
      if (ram[i] < '0' || rem[i] > '9') {
        yes = 0;
        break;
      }
    }
  }
  if (yes == 0)
    printf("No\n");
  else
    printf("Yes\n");
}
