View Compilation Error

0_0_25417102_31641.cpp:37:11: error: '::main' must return 'int'
 void main()
           ^
0_0_25417102_31641.cpp: In function 'int main()':
0_0_25417102_31641.cpp:43:31: error: 'memset' was not declared in this scope
     memset(flag,0,sizeof(flag));
                               ^