foo.cpp: In function 'void Init(const int&)':
foo.cpp:22:30: error: 'memset' was not declared in this scope
     memset(cnt, 0, sizeof cnt);
                              ^
foo.cpp: In function 'int main()':
foo.cpp:51:11: error: 'INT_MAX' was not declared in this scope
     ans = INT_MAX; 
           ^
foo.cpp:54:14: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
         W = L+R >>1;
              ^