#include <bits/stdc++.h>
using namespace std;

int a, b, c;

long long s1(int a, int b, int c) {
    long long ans = 0;
    for (int i = 1; i <= a; i++) {
        int least = i + 1;
        int most = min({a, b - i, c - i});
        if (least <= most)
            ans += most - least + 1; 
    }
    return ans;
}

long long s2(int a, int b, int c) {
    long long ans = 0;
    for (int i = 1; i <= b; i++) {
        int least = 1;
        int most = min({i - 1, a - i, c - i});
        if (least <= most)
            ans += most - least + 1;
    }
    return ans;
}

int main() {
    cin >> a >> b >> c;
    long long p = s1(a, b, c) + s1(a, c, b) + s1(b, a, c) + s1(b, c, a) + s1(c, a, b) + s1(c, b, a);
    long long q = s2(a, b, c) + s2(a, c, b) + s2(b, a, c) + s2(b, c, a) + s2(c, a, b) + s2(c, b, a);
//    fprintf(stderr, "p = %lld, q = %lld\n", p, q);
    long long res = 8 * p + 8 * q;
    cout << res / 2;
}