/in/foo.cc: In function 'int main()':
/in/foo.cc:72:19: error: 'i' was not declared in this scope
     s1.jiaoji(a1, i, a2, j);
                   ^
/in/foo.cc:72:26: error: 'j' was not declared in this scope
     s1.jiaoji(a1, i, a2, j);
                          ^
/in/foo.cc:75:26: error: 'k' was not declared in this scope
     s2.jiaoji(a1, i, a3, k);
                          ^