#include<iostream>
#include<cstdio>

using namespace std;

int main(void)
{
    int i,x,y,sum,t;
    scanf("%d%d",&x,&y);
    if(x>y){
        i = y+1;
        t = x;
    }
    else{
         i = x+1;
         t = y;
    }
    for(sum=0;i<t;i++)
    {
        if(i%2!=0)
        {
            sum+=i;
        }
        else continue;
    }
    printf("%d\n",sum);
    return 0;
}