can som1 tell me wats wrong with this code plz (im still learning and need to lear my mistakes

)
here:
// mastrgamr's simple calculator!
#include <iostream.h>
void main()
{
cout<<"to use my calculator follow the first command
then u must hold shift and either A to add, S to subtract,
M to multiply, or D to divide. insert another number and your
answer should appear!"<< endl;
float num2;
float num1;
char op;
char (op==65 && op==83 && op==77 && op==68)
float ans;
cout << "insert number: ";
cin >> num1;
cin >> op;
if (op==65);
ans=num1+num2;
if (op==83)
ans=num1-num2;
if (op==77)
ans=num1*num2;
if (op==68)
ans=num1/num2;
cin >> num2>> endl;
cout << "=" << ans << endl;
}
i dont understand wat my CMD is talking about wen it anounces my errors