foo.cc: In function 'int main()':
foo.cc:6:19: warning: right operand of comma operator has no effect [-Wunused-value]
    6 |         cin >> x,y;
      |                   ^
foo.cc:7:16: warning: 'y' is used uninitialized [-Wuninitialized]
    7 |         t = abs(x - y);
      |             ~~~^~~~~~~
foo.cc:5:18: note: 'y' was declared here
    5 |         double x,y,t,m;
      |                  ^

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