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0_0_20505261_19946.cpp: In function 'int main()':
0_0_20505261_19946.cpp:112:11: error: converting to 'std::tuple<double, int, double, double>' from initializer list would use explicit constructor 'constexpr std::tuple< <template-parameter-1-1> >::tuple(_UElements&& ...) [with _UElements = {double&, int, double&, double&}; <template-parameter-2-2> = void; _Elements = {double, int, double, double}]'
    x[i<<1]={x1,1,y1,y2};
           ^