12 lines
225 B
C++
12 lines
225 B
C++
#include <bits/stdc++.h>
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using namespace std;
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const double eps = 1e-6;
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int main() {
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int n;
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double s = 0;
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cin >> n;
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for (double i = 0.1; n - i > eps; i += 0.1) s += i;
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cout << s;
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return 0;
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} |