29 lines
407 B
C++
29 lines
407 B
C++
#include<cstdio>
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const int maxn=100010;
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int x,y,fa[maxn];
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int ff(int x)
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{
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return fa[x]!=x?fa[x]=ff(fa[x]):x;
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}
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int main()
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{
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#ifdef local
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freopen("pro.in","r",stdin);
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#endif
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while(scanf("%d",&x)==1)
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{
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for(int i=0;i<maxn;i++) fa[i]=i;
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int res=0;
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while(x!=-1)
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{
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scanf("%d",&y);
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x=ff(x);y=ff(y);
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if(x==y) ++res;
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else fa[x]=y;
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scanf("%d",&x);
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}
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printf("%d\n",res);
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}
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return 0;
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}
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