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#include <cstdio>
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long long f[4];
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int main()
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{
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f[1] = 1;
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int n;
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scanf("%d", &n);
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for (int i = 2; i <= n; i++)
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f[i & 3] = ((f[(i - 1) & 3] << 1) + f[(i - 2) & 3]) % 1000000007;
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printf("%lld", f[n & 3]);
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return 0;
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} |
