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#include <cstdio>
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const int N = 1 << 16 | 1;
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int phi[N];
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int main()
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{
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for (int i = 2; i < N; i++) if (!phi[i])
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for (int j = i; j < N; j += i)
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{
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if (!phi[j]) phi[j] = j;
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phi[j] = phi[j] / i * (i - 1);
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}
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for (int p; ~scanf("%d", &p);)
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printf("%d\n", phi[p - 1]);
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return 0;
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} |
