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30 lines
489 B
C++
30 lines
489 B
C++
#include <iostream>
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#include <limits>
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using std::cin;
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using std::cout;
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const char endl = '\n';
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const int N = 2e5 + 5;
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int n, x, a, b;
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long long sum, ans = std::numeric_limits<long long>::max();
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int main() {
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std::ios::sync_with_stdio(false);
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cin.tie(nullptr);
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cin >> n >> x;
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for (int i = 1; i <= std::min(x, n); i++) {
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cin >> a >> b;
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sum += a + b;
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ans = std::min(ans, sum + 1ll * (x - i) * b);
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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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