Входная строка имела неверный формат, как как лучше переделать?

private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {
Single a, b, c, d, f, g, h, m, k, n, p;	 
Single A = Single::TryParse(textBox1->Text,
System::Globalization::NumberStyles::Number,
System::Globalization::NumberFormatInfo::CurrentInfo, a);
Single B = Single::TryParse(textBox2->Text,
System::Globalization::NumberStyles::Number,
System::Globalization::NumberFormatInfo::CurrentInfo, b);
Single N = Single::TryParse(textBox4->Text,
System::Globalization::NumberStyles::Number,
System::Globalization::NumberFormatInfo::CurrentInfo, n);
if(radioButton1->Checked){
g=40;
h=3;
}
else   {
g=90;
h=5;}
if (b>=2) {
m=0.9; } 
else  {
m=1; }
c = a-10;
d = (c*h+g)*b;
k = d*m+0.1;
p = n-k;
textBox3->Text = String::Format("{0:F0}", k);
textBox5->Text = String::Format("{0:F0}", p);
			 }