View Compilation Error

0_0_32972411_7981.cpp: In function 'int main()':
0_0_32972411_7981.cpp:8:19: error: invalid types 'int[int]' for array subscript
    scanf("%d",&a[i]);
                   ^
0_0_32972411_7981.cpp:16:22: error: '__gcd' was not declared in this scope
    a=a/__gcd(a,arr[i])*arr[i];
                      ^
0_0_32972411_7981.cpp:16:22: note: suggested alternative:
In file included from GCC4.9.2/x86_64-w64-mingw32/include/c++/algorithm:62:0,
                 from 0_0_32972411_7981.cpp:2:
GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/stl_algo.h:1229:5: note:   'std::__gcd'
     __gcd(_EuclideanRingElement __m, _EuclideanRingElement __n)
     ^