View Compilation Error

0_0_17630940_12833.cpp: In function 'double calc(double)':
0_0_17630940_12833.cpp:25:8: error: redefinition of 'double calc(double)'
 double calc(double xx)
        ^
0_0_17630940_12833.cpp:14:8: note: 'double calc(double)' previously defined here
 double calc(double xx)
        ^
0_0_17630940_12833.cpp:31:25: error: 'struct Node' has no member named 'y'
         sum+=d*d*d*a[i].y;
                         ^
0_0_17630940_12833.cpp: In function 'int main()':
0_0_17630940_12833.cpp:69:16: error: redeclaration of 'double g'
         double g=calc(l);
                ^
0_0_17630940_12833.cpp:63:16: note: 'double g' previously declared here
         double g=calc(l);
                ^
0_0_17630940_12833.cpp:70:16: error: redeclaration of 'double h'
         double h=calc(r);
                ^
0_0_17630940_12833.cpp:64:16: note: 'double h' previously declared here
         double h=calc(r);
                ^