// Skyqwq
#include <bits/stdc++.h>

#define pb push_back
#define fi first
#define se second
#define mp make_pair

using namespace std;

typedef pair<int, int> PII;
typedef long long LL;

template <typename T> bool chkMax(T &x, T y) { return (y > x) ? x = y, 1 : 0; }
template <typename T> bool chkMin(T &x, T y) { return (y < x) ? x = y, 1 : 0; }

template <typename T> void inline read(T &x) {
    int f = 1; x = 0; char s = getchar();
    while (s < '0' || s > '9') { if (s == '-') f = -1; s = getchar(); }
    while (s <= '9' && s >= '0') x = x * 10 + (s ^ 48), s = getchar();
    x *= f;
}

LL ans;

LL A, B, C;

int c[10];

int d[6];

int t;

LL cnt;

int w[3][3], f[3][3], mb[3], mx[3];

typedef pair<LL, LL> PLL;

typedef pair<PLL, LL> POO;

map<POO, LL> O;


LL inline calc(LL a, LL b, LL c){
	if (O.count(mp(mp(a, b), c))) return O[mp(mp(a, b), c)];
	LL tt = 0;
	for (int i = 1; i <= a; i++) {
		LL lb = i + 1, rb = min(c - i, b);
		if (lb <= rb) tt += rb - lb + 1;
	}
	return O[mp(mp(a, b), c)] = tt;
}

void inline chk() {
	w[1][0] = d[0];
	w[1][1] = d[1];
	w[1][2] = d[2];
	w[2][0] = d[3];
	w[2][1] = d[4];
	w[2][2] = d[5];
	int o = 0;

	for (int i = 0; i < 3; i++) {
		for (int j = 0; j < i; j++) {
			bool op = 1;			
			for (int k = 0; k < 3; k++) {
				f[o][k] = abs(w[i][k] - w[j][k]);
				if (f[o][k]) op = 0;
			}
			if (op) return ;
			o++;
		}
	}
	memset(mx, 0, sizeof mx);
	for (int i = 0; i < 3; i++) {
		sort(f[i], f[i] + 3);
		for (int j = 0; j < 3; j++) {
			chkMax(mx[j], abs(w[i][j]));
			if (f[i][j] != mb[j]) return ;
		}
	}

	LL ma = 2e9, mb = 2e9, mc = 2e9;
	for (int i = 0; i < 3; i++) {
		if (mx[i] == 1000) {
			chkMin(mb, i == 0 ? A : (i == 1 ? B : C));
			chkMin(ma, i == 0 ? A : (i == 1 ? B : C));
		} else if (mx[i] == 1001) {
			chkMin(mc, i == 0 ? A : (i == 1 ? B : C));
			chkMin(mb, i == 0 ? A : (i == 1 ? B : C));
			chkMin(ma, i == 0 ? A : (i == 1 ? B : C));
		} else assert(false);
	}

	ans += calc(ma, mb, mc);
	// cout << ma << " " << mb << " " << mc << " " << calc(ma, mb, mc) << " why?\n";
	// for (int i = 0; i < 3; i++) {
	// 	for (int j = 0; j < 3; j++) {
	// 		cout << w[i][j] << ", ";
	// 	}
	// 	cout << endl;
	// }
	// puts("");
}

void dfs(int u) {
	if (u == 6) {
		chk();
		return;
	}
	for (int i = 1; i <= t; i++) {
		d[u] = c[i];
		dfs(u + 1);
	}
}

int main() {
    read(A), read(B), read(C);
    if (A > B) swap(A, B);
    if (A > C) swap(A, C);
    if (B > C) swap(B, C);
    LL L = min(A, min(B, C));
    // 1

    LL zg = 0;
    for (LL i = 1; i <= L; i++) {
    	zg += i - 1;
    	if (i % 2 == 0) zg--;
    }
    cnt = 0;
    t = 0;
    mb[0] = 1;
    mb[1] = 1000;
    mb[2] = 1001;
    c[++t] = 1;
    c[++t] = -1;
    c[++t] = 0;
    c[++t] = 1000;
    c[++t] = -1000;
    c[++t] = 1001;
    c[++t] = -1001;
    dfs(0);
  
    ans /= 2;
    printf("%lld\n", ans);
    return 0;
}