24 lines
431 B
C++
24 lines
431 B
C++
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#include <bits/stdc++.h>
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using namespace std;
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const int N = 10010;
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int b[N];
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int l;
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int m;
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int cnt;
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int main() {
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scanf("%d %d", &l, &m);
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for (int i = 0; i <= l; i++) b[i] = 1;
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while (m--) {
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int u, v;
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scanf("%d %d", &u, &v);
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for (int i = u; i <= v; i++) b[i]--;
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}
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for (int i = 0; i <= l; i++)
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if (b[i] == 1) cnt++;
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printf("%d", cnt);
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return 0;
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}
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