/in/foo.cc: In function 'int reach(int*)':
/in/foo.cc:23:9: warning: unused variable 'flag' [-Wunused-variable]
     int flag = 1;
         ^~~~
/in/foo.cc: In function 'void dfs(int*, int*, int, int)':
/in/foo.cc:40:23: warning: left operand of comma operator has no effect [-Wunused-value]
     for (int i = w; i <= 9, c[i] != 3; i++) {
                     ~~^~~~