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- #include<bits/stdc++.h>
- using namespace std;
- const int MOD = 1000000;
- int main() {
- int n;
- cin >> n;
- if (n > 24)n = 24;//注意到25!末尾已经有6个0不会对计算结果产生影响
- int s = 0;
- for (int i = 1; i <= n; i++) {
- int p = 1;
- for (int j = 2; j <= i; j++) {
- p = p * j % MOD;
- }
- s = (s + p) % MOD;
- }
- cout << s << endl;
- return 0;
- }
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