C. Sum of Range

#include <iostream>
#include<bits/stdc++.h>
#define ll long long
#define ull unsigned long long
using namespace std;

ll summation(ll x, ll y ){
    return (y * (y + 1) / 2) - (x * (x - 1) / 2);
}
ll sum_even(ll x , ll y){

    return (y * (y + 2) / 4) - (x * (x - 2) / 4);
}
ll sum_odd(ll x, ll y ){
    return ( ( ( (y + 1) / 2) *( (y - 1) / 2) ) - ( ( (x - 1) / 2) * ( (x - 1) / 2) ) );
}

int main() {
   ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);

ll a,b;
cin>>a>>b;
ll x= min(a,b);
ll y= max(a,b);

cout<<summation(x,y)<<"\n";
cout<<sum_even(x,y)<<"\n";
cout<<sum_odd(x,y)<<"\n";
    return 0;
}