サブシーケンスの和

#include
int main(){
    int count = 0;
    while (1){
        int n = 0;
        int m = 0;
        scanf("%d", &n);
        scanf("%d", &m);
        if (n == m&&n == 0){
            break;
        }
        count++;
        double sum = 0;
        for (int i = n; i <= m;i++){
            sum += 1.0 / i / i;
        }
        printf("Case %d:%.5f
",count,sum);
    }
    return 0;
}