32 lines
670 B
C++
32 lines
670 B
C++
#include <cstdio>
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using namespace std;
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int n, m;
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int a[100], b[100];
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int main() {
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scanf("%d%d", &n, &m);
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for (int i = 1; i <= n; ++i)
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a[i] = b[i] = 0;
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for (int i = 1; i <= m; ++i) {
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int x, y;
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scanf("%d%d", &x, &y);
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if (a[x] < y && b[y] < x) {
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if (a[x] > 0)
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b[a[x]] = 0;
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if (b[y] > 0)
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a[b[y]] = 0;
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a[x] = y;
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b[y] = x;
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}
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}
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int ans = 0;
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for (int i = 1; i <= n; ++i) {
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if (a[i] == 0)
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++ans;
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if (b[i] == 0)
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++ans;
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}
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printf("%d", ans);
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return 0;
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}
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