View Compilation Error

0_0_18209307_11517.cpp: In function 'int main()':
0_0_18209307_11517.cpp:28:34: error: 'f' cannot be used as a function
                     f[i][j]=f(i,j)+1;  
                                  ^
0_0_18209307_11517.cpp:32:40: error: 'f' cannot be used as a function
                     f[i][j]=max(f(i-1,j),f(i,j-1));  
                                        ^
0_0_18209307_11517.cpp:32:49: error: 'f' cannot be used as a function
                     f[i][j]=max(f(i-1,j),f(i,j-1));  
                                                 ^