import std.stdio, std.string, std.range, std.conv, std.array, std.algorithm, std.math, std.typecons, std.ascii;

void main() {
    int A, B;
    readf("%d %d\n", &A, &B);
    auto S = readln.chomp;
    writeln(S[A] == '-' && (S[0..A]~S[A+1..$]).all!isDigit ? "Yes" : "No");
}

