/in/foo.cc: In function 'int main()':
/in/foo.cc:58:19: error: expected ';' before ')' token
  for(int i=n-1,k=0)i>=0;i--){//k:字母出现的个数 
                   ^
/in/foo.cc:58:19: error: expected primary-expression before ')' token
/in/foo.cc:58:19: error: expected ';' before ')' token
/in/foo.cc:58:21: warning: statement has no effect [-Wunused-value]
  for(int i=n-1,k=0)i>=0;i--){//k:字母出现的个数 
                    ~^~~
/in/foo.cc:58:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  for(int i=n-1,k=0)i>=0;i--){//k:字母出现的个数 
  ^~~
/in/foo.cc:58:25: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for'
  for(int i=n-1,k=0)i>=0;i--){//k:字母出现的个数 
                         ^
/in/foo.cc:58:16: warning: unused variable 'k' [-Wunused-variable]
  for(int i=n-1,k=0)i>=0;i--){//k:字母出现的个数 
                ^
/in/foo.cc:58:25: error: 'i' was not declared in this scope
  for(int i=n-1,k=0)i>=0;i--){//k:字母出现的个数 
                         ^