#include <stdio.h>
intmain()
{ 
    int low,high,sum = 0;
    scanf("%d %d",&low,&high);
    if (low < 1 || high < 1 || low > high)
    { printf("Invalid input");
    }
    int sum=0;
    for(int i=low; i <= high; i++)
    { 
        if(i%7 == 0)
        { sum +=i;
        }
    } 
    printf("%d",sum);
    return 0;
}