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class Rei11_1{
    public static void main(String[] args){
        GoukeiKeisan gk = new GoukeiKeisan();

        gk.setOperand(1, 10);
        gk.sum();
        System.out.println("1〜10までの和は" + gk.ans + "です");

        int ans = gk.sum(5, 10);
        System.out.println("5〜10までの和は" + ans + "です");
    }
}

class GoukeiKeisan{
    int ope1;
    int ope2;
    int ans;

    void setOperand(int a, int b){
        ope1 = a;
        ope2 = b;
    }

    void sum(){
        ans = 0;
        for(int i=ope1; i<=ope2; i++){
            ans += i;
        }
    }

    int sum(int a, int b){
        ans = 0;
        for(int i=a; i<=b; i++){
            ans += i;
        }
        return ans;
    }
}