View Compilation Error

0_0_21580133_28484.cpp:3:11: error: '::main' must return 'int'
 void main() {
           ^
0_0_21580133_28484.cpp: In function 'int main()':
0_0_21580133_28484.cpp:7:21: error: return-statement with no value, in function returning 'int' [-fpermissive]
         if (a == 0) return ;
                     ^