/in/foo.cc: In function 'int main()':
/in/foo.cc:14:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0;i <= max(a, b);i++)f[0][i] = 1;
                    ~~^~~~~~~~~~~~
/in/foo.cc:17:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 1;i <= n;i++) {
                    ~~^~~~
/in/foo.cc:18:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int j = 0;j <= max(a, b);j++) {
                        ~~^~~~~~~~~~~~