foo.cc: In function 'int main()':
foo.cc:230:16: warning: statement has no effect [-Wunused-value]
  230 |       b[i-1][j]=='R';
      |       ~~~~~~~~~^~~~~
foo.cc:232:16: warning: statement has no effect [-Wunused-value]
  232 |       b[i+1][j]=='R';
      |       ~~~~~~~~~^~~~~
foo.cc:234:16: warning: statement has no effect [-Wunused-value]
  234 |       b[i][j-1]=='R';
      |       ~~~~~~~~~^~~~~
foo.cc:236:16: warning: statement has no effect [-Wunused-value]
  236 |       b[i][j+1]=='R';
      |       ~~~~~~~~~^~~~~
foo.cc:241:16: warning: statement has no effect [-Wunused-value]
  241 |       b[i-1][j]=='S';
      |       ~~~~~~~~~^~~~~
foo.cc:243:16: warning: statement has no effect [-Wunused-value]
  243 |       b[i+1][j]=='S';
      |       ~~~~~~~~~^~~~~
foo.cc:245:16: warning: statement has no effect [-Wunused-value]
  245 |       b[i][j-1]=='S';
      |       ~~~~~~~~~^~~~~
foo.cc:247:16: warning: statement has no effect [-Wunused-value]
  247 |       b[i][j+1]=='S';
      |       ~~~~~~~~~^~~~~
foo.cc:252:16: warning: statement has no effect [-Wunused-value]
  252 |       b[i-1][j]=='P';
      |       ~~~~~~~~~^~~~~
foo.cc:254:16: warning: statement has no effect [-Wunused-value]
  254 |       b[i+1][j]=='P';
      |       ~~~~~~~~~^~~~~
foo.cc:256:16: warning: statement has no effect [-Wunused-value]
  256 |       b[i][j-1]=='P';
      |       ~~~~~~~~~^~~~~
foo.cc:258:16: warning: statement has no effect [-Wunused-value]
  258 |       b[i][j+1]=='P';
      |       ~~~~~~~~~^~~~~

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