View Compilation Error

0_0_15712842_17905.cpp: In function 'int main()':
0_0_15712842_17905.cpp:19:10: error: conflicting declaration 'int a'
  int n,i,a,b;
          ^
0_0_15712842_17905.cpp:18:6: note: previous declaration as 'int a [1000]'
  int a[1000];
      ^
0_0_15712842_17905.cpp:24:9: error: invalid operands of types 'int [1000]' and 'int' to binary 'operator*'
    a=(a*b)/gcd(a,b);
         ^
0_0_15712842_17905.cpp:24:19: error: invalid conversion from 'int*' to 'int' [-fpermissive]
    a=(a*b)/gcd(a,b);
                   ^
0_0_15712842_17905.cpp:10:5: note: initializing argument 1 of 'int gcd(int, int)'
 int gcd(int a,int b)
     ^