foo.cc: In function 'void solve()':
foo.cc:9:2: error: 'ans' was not declared in this scope
  ans=(((a%MOD*(d%MOD)%MOD-(b%MOD*(c%MOD)%MOD+MOD)%MOD+MOD)%MOD;
  ^~~
foo.cc:9:2: note: suggested alternative: 'abs'
  ans=(((a%MOD*(d%MOD)%MOD-(b%MOD*(c%MOD)%MOD+MOD)%MOD+MOD)%MOD;
  ^~~
  abs
foo.cc:9:63: error: expected ')' before ';' token
  ans=(((a%MOD*(d%MOD)%MOD-(b%MOD*(c%MOD)%MOD+MOD)%MOD+MOD)%MOD;
                                                               ^
foo.cc:9:63: error: expected ')' before ';' token

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