What is the output of this program?

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#include
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using namespace std;
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class sample;
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class sample1
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{
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int width, height;
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public:
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int area ()
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{
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return (width * height);}
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void convert (sample a);
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};
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class sample
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{
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private:
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int side;
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public:
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void set_side (int a)
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{
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side = a;
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}
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friend class sample1;
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};
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void sample1::convert (sample a)
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{
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width = a.side;
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height = a.side;
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}
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int main ()
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{
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sample sqr;
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sample1 rect;
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sqr.set_side(6);
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rect.convert(sqr);
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cout