import sys
input = sys.stdin.readline
a = int(input())
b = int(input())
f = abs(a - b) // 2
s = (abs(a - b) + 1) // 2
print(f * (f + 1) // 2 + s * (s + 1) // 2)#include<iostream>
using namespace std;
int main(){
int a,b;
cin>>a>>b;
if(a>b){
int temp=a;
a=b;
b=temp;
}
if((b-a)%2==0||(a-b)%2==0){
int c=(b-a)/2;
int sum=0;
for(int i=1;i<=c;i++){
sum=sum+i;
}
cout<<2*sum<<endl;
}
else{
int m=(b-a+1)/2;
int sum1=0;
for(int i=1;i<=m;i++){
sum1=sum1+i;
}
int m1=(b-a-1)/2;
int sum2=0;
for(int i=1;i<=m1;i++){
sum2=sum2+i;
}
cout<<(sum1+sum2)<<endl;
}
}
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