Wrong Answer
/in/foo.cc: In function 'void chgs(int, int)':
/in/foo.cc:28:5: warning: unused variable 'ans' [-Wunused-variable]
ll ans=0;
^~~
/in/foo.cc: In function 'void chgs(int, int)':
/in/foo.cc:28:5: warning: unused variable 'ans' [-Wunused-variable]
ll ans=0;
^~~
