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18 lines
439 B
C++
18 lines
439 B
C++
#include <bits/stdc++.h>
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using namespace std;
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int main() {
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long long n, m, ans;
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cin >> n >> m;
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n++, m++;
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ans = n * m * (n * m - 1) * (n * m - 2) / 6 - n * m * (m - 1) * (m - 2) / 6 - m * n * (n - 1) * (n - 2) / 6;
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for (long long i = 1; i <= n; i++) {
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for (long long j = 1; j <= m; j++) {
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ans -= 2ll * (__gcd(i, j) - 1) * (n - i) * (m - j);
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}
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}
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cout << ans << endl;
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return 0;
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}
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