15 lines
286 B
C
15 lines
286 B
C
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#include <stdlib.h>
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#include <stdio.h>
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int main(int argc, char* argv[]) {
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int n = atoi(argv[1])-1;
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int p = n/3;
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int q = n/5;
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int r = n/15;
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int s = 3*((p*(p+1))/2) +
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5*((q*(q+1))/2) -
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15*((r*(r+1))/2);
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printf("%d\n", s);
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return 0;
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}
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