26,10,16

include

include

using namespace std;
int main(){
double a,c; //注意题目是实数还是整数
char b;
cin>>a>>b>>c;
switch(b){ //switch（） 后要有个{}
case'+':{cout<<fixed<<setprecision(2)<<a+c<<endl;break;} //break要放在花括号里面，endl后一定要有个；
case'-':{cout<<fixed<<setprecision(2)<<a-c<<endl;break;}
case'':{cout<<fixed<<setprecision(2)<<ac<<endl; break;}
case'/':if(c!=0){cout<<fixed<<setprecision(2)<<a/c<<endl;}
else{cout<<"The divisor is 0."<<endl;}
break;}
return 0;
}