View Compilation Error

0_0_20825092_714.cpp:3:12: error: '::main' must return 'int'
 void  main()
            ^
0_0_20825092_714.cpp: In function 'int main()':
0_0_20825092_714.cpp:7:26: error: 'scanf' was not declared in this scope
     while(scanf("%lld",&n)!=EOF){
                          ^
0_0_20825092_714.cpp:7:29: error: 'EOF' was not declared in this scope
     while(scanf("%lld",&n)!=EOF){
                             ^
0_0_20825092_714.cpp:18:23: error: 'printf' was not declared in this scope
         printf("TAT\n");
                       ^
0_0_20825092_714.cpp:20:20: error: 'printf' was not declared in this scope
     printf("%d\n",y);
                    ^