19 lines
360 B
C++
19 lines
360 B
C++
#include<cstdio>
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#include<cstring>
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int main()
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{
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int x,y,ans=0;
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bool isp[100010];
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memset(isp,1,sizeof(isp));
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isp[0]=isp[1]=0;
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for(int i=2;i*i<100010;i++)
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if(isp[i])
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for(int j=2;j*i<100010;j++)
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isp[j*i]=0;
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scanf("%d%d",&x,&y);
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if(x<=y) for(int i=x;i<=y;i++) ans+=isp[i];
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else for(int i=y;i<=x;i++) ans+=isp[i];
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printf("%d\n",ans);
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return 0;
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}
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