#include <iostream>
#include <sstream>
#include <string>

using namespace std;

int main() {
  char cexpr[256];
  double opnd1, opnd2;
  char op;
  cout << "Enter arithmetic expression: ";
  cin.getline(cexpr, 256);
  istringstream sstream(cexpr);
  sstream >> opnd1 >> op >> opnd2;
  double result=0;
  switch(op) {
    case '+':
      result = opnd1 + opnd2;
      break;
    case '-':
      result = opnd1 - opnd2;
      break;
    case '*':
      result = opnd1 * opnd2;
      break;
    case '/':
      result = opnd1 / opnd2;
      break;
    default:
      cout << "ERROR\n";
      break;
  }
  cout << result << endl;
}