#include <iostream> // input / output stream
#include <math.h>

using namespace std;

int main() {
 // Çàäà÷à ¹4.  Êàëüêóëÿòîð.
 cout << "Please enter a_b, where's '_' mean '*','/','+' or'-':" << endl;
 double a, b, result;
 char c;
 cin >> a >> c >> b;
 if (c == '*') {
 	result = a*b;
	cout << result << endl;
 }
 else if (c== '/') {
 	result = a/b;
 	cout << result << endl;
 }
 else if (c == '-'){
 	result = a - b;
 	cout << result << endl;
 }
 else if (c == '+') {
 	result = a + b;
 	cout << result << endl;
 } 
 }