/in/foo.cc: In function 'bool check(int)':
/in/foo.cc:9:9: warning: unused variable 'tmp' [-Wunused-variable]
     int tmp=x;
         ^~~
/in/foo.cc: In function 'int nxt(int)':
/in/foo.cc:20:22: warning: suggest parentheses around comparison in operand of '&' [-Wparentheses]
     if (y%400==0||y%4==0&y%100!=0) day[2]=29;
                   ~~~^~~