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21 lines
318 B
C++
21 lines
318 B
C++
#include <iostream>
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#include <iomanip>
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#include <cstring>
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#include <cstdio>
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#include <ctime>
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#include <cmath>
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using namespace std;
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int main(){
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int a;
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double sum1,sum2;
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scanf("%d",&a);
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for(int i=1;i<=a;i+=2){
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sum1+=1*1.0/i;
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}
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for(int i=2;i<=a;i+=2){
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sum2+=1*1.0/i;
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}
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printf("%.4lf",sum1-sum2);
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return 0;
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}
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