18 lines
249 B
C++
18 lines
249 B
C++
#include<iostream>
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#include<sstream>
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using namespace std;
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int main()
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{
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string a;
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int n;
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stringstream li;
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cin>>n;
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for(int i=1;i<=n;i++) li<<i;
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li>>a;
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int ans=0;
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for(int i=0;i<a.size();i++) if(a[i]=='1') ans++;
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cout<<ans<<endl;
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return 0;
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}
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