26 lines
490 B
C
26 lines
490 B
C
#include <stdio.h>
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int pr(long long n);
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int main() {
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long long int x,i;
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printf("Num: ");
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if(!(scanf("%lld",&x)))return 1;
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for(i = x; i > 1; --i)
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if(pr(i))
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printf("%lld\t",i);
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return 0;
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}
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int pr(long long n) {
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if (n < 2) return 0;
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if (n == 2 || n == 3) return 1;
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if (n % 2 == 0 || n % 3 == 0) return 0;
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for (long long i = 5; i * i <= n; i += 6) {
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if (n % i == 0 || n % (i + 2) == 0)
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return 0;}
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return 1;
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}
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