40 lines
429 B
C
40 lines
429 B
C
#include <stdio.h>
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#include <math.h>
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char prime(unsigned long long m)
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{
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unsigned long i;
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for (i = 3; i <= sqrt(m); i += 2)
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if (m % i == 0)
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return 0;
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return 1;
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}
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int main()
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{
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unsigned long long n, i;
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scanf("%lld", &n);
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if (n == 1) {
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puts("2");
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return 0;
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}
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i = (n % 2) ? n : n - 1;
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while (i <= 18446744073709551615ULL) {
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i += 2;
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if (!prime(i))
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continue;
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printf("%lld\n", i);
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return 0;
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}
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}
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