#include <stdio.h>
int main() {
    int youngest_age, oldest_age;
    int sum_divisible_by_seven = 0;
    scanf("%d", &youngest_age);
    scanf("%d", &oldest_age);
    if (youngest_age < 0 || oldest_age < 0 || youngest_age > oldest_age) {
        printf("Issue with the input: Invalid age range or negative age provided.\n");
    }else {
        for (int age = youngest_age; age <= oldest_age; age++) {
            if (age % 7 == 0) {
                sum_divisible_by_seven += age;
            }
        }
        printf("The sum of ages divisible by seven in the range is: %d\n", sum_divible_by_seven);
    }
    return 0;
        
}