#include <bits/stdc++.h>
using namespace std;
long long sum[11451], cnt, cn;

int main() {
	long long s1, s2, s3;
	cin >> s1 >> s2 >> s3;
	for (long long i = 1; i <= s1; i++) {
		for (long long j = 1; j <= s2; j++) {
			for (long long k = 1; k >= s3; k++) {
				cnt++;
				sum[cnt] = i + j + k;
			}
		}
	}
	for (long long i = 1; i <= cnt; i++) {
		for (long long j = i + 1; j <= cnt; j++) {
			if (sum[i] == sum[j]) {
				cn++;
			}
		}
	}
	cout << cn;
	return 0;
}