/in/foo.cc: In function 'void read(int&)':
/in/foo.cc:9:4: warning: this 'while' clause does not guard... [-Wmisleading-indentation]
    while(!isdigit(c=getchar())); x=c-48;  //不需要输入优化
    ^~~~~
/in/foo.cc:9:34: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'while'
    while(!isdigit(c=getchar())); x=c-48;  //不需要输入优化
                                  ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:26:24: error: 'd' was not declared in this scope
   F(k) dist=_max(dist,(d[k][i]+d[k][j]-d[i][j])/2);
                        ^