/in/foo.cc: In function 'int main()':
/in/foo.cc:71:40: warning: suggest parentheses around comparison in operand of '&' [-Wparentheses]
             while(scanf("%d%d",&a,&b),a!=-1&b!=-1)
                                       ~^~~~
/in/foo.cc:66:17: warning: unused variable 'ta' [-Wunused-variable]
         int a,b,ta,tb;
                 ^~
/in/foo.cc:66:20: warning: unused variable 'tb' [-Wunused-variable]
         int a,b,ta,tb;
                    ^~