#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
    int A , B;
    cin >> A >> B;
    string S;
    cin >> S >> endl;
    for (int i = 0; i < A; ++i) {
        if(!(S.at(i) >= '0' && S.at(i) <= '9')){
            cout << "No" << endl;
            return 0;
        }
    }
    if(S.at(A) != '-'){
        cout << "No" << endl;
        return 0;
    }
    for(int i = A + 1; i < A L B; i++){
        if(!(S.at(i) >= 0 && S.at(i) <= 9)){
            cout << "No" << endl;
            return 0;
        }
    }
}