output_description: Evaluate the formula and print the result.
  
  * * *
input_description: The input is given from Standard Input in the following format:
  
      
      
      A op B
attempt: #include <iostream>
  #include <string>
  #include <vector>
  #include <algorithm>
  #include <cmath>
  #include <stack>
  #include <queue>
  #include <numeric>
  #include <iomanip>
  #include <map>
  #include <set>
  #include <deque>
  #include <utility>
  using namespace std;
  using ll = long long;
  #define rep(i, n) for (int i = 0; i < n; i++)
  #define repk(i, k, n) for (int i = k; i < n; i++)
  #define MOD 1e9 + 7
  #define INF 1e9
  #define SENTINEL 2e9
  #define PIE 3.14159265358979323
  
  template <class T>
  inline bool chmin(T &a, T b){if (a > b){a = b;return true;}return false;}
  template <class T>
  inline bool chmax(T &a, T b){if (a < b){a = b;return true;}return false;}
  template <class T>
  inline T GCD(T a, T b){if (b == 0) return a; else return GCD(b, a % b);}
  template <class T>
  inline T LCM(T a, T b) {return (a * b) / GCD(a, b);}
  
  void ans(bool flag){
      if (flag)
          cout << "Yes" << endl;
      else
          cout << "No" << endl;
  }
  
  int main(){
      int a, b;
      string s;
      cin >> a >> s >> b;
      if (s=="+")
          cout << a + b << endl;
          else
              cout << a - b << endl;
  }
problem_description: Statement
  
  Joisino wants to evaluate the formula "A op B". Here, A and B are integers,
  and the binary operator op is either `+` or `-`. Your task is to evaluate the
  formula instead of her.
samples: [{"input": "1 + 2", "output": "3\n    \n\nSince 1 + 2 = 3, the output should be 3.\n\n* * *"}, {"input": "5 - 7", "output": "-2"}]