Total average score

#include
using namespace std;
int main(){
    int khmer, math, english, average;
    cout<<"Input Khmer score:"; cin>>khmer;
    cout<<"Input Math score:"; cin>>math;
    cout<<"Input English score:"; cin>>english;
    average=(khmer+math+english)/3;
    cout<<"score of average: "; cout<    if(average>=90)
        cout<<"A";
    else if(average>80)
        cout<<"B";
     else if(average>70)
        cout<<"C";
     else if(average>60)
        cout<<"D";
     else if(average>50)
    {
        cout<<"E";
    }else if(average<=50)
    cout<<"F";
   
    return 0;
}