19/12/18 00:09:07.64 i+6d3gEf.net
>>346 C
int s(int n){ return (1000/n)*(1000/n+1)/2*n; }
int main(){ return s(3)+s(5)-s(15); }
19/12/18 00:09:07.64 i+6d3gEf.net
>>346 C
int s(int n){ return (1000/n)*(1000/n+1)/2*n; }
int main(){ return s(3)+s(5)-s(15); }