View Compilation Error

0_0_18281439_19761.cpp: In function 'int main()':
0_0_18281439_19761.cpp:6:11: error: conflicting declaration 'double a'
  double s,a=0;
           ^
0_0_18281439_19761.cpp:5:6: note: previous declaration as 'int a'
  int a,b,i;
      ^