View Compilation Error

0_0_16806012_20994.cpp: In function 'int main()':
0_0_16806012_20994.cpp:18:20: error: 'm' was not declared in this scope
    printf("%d %d",(m+n)/2,(m-n)/2);
                    ^
0_0_16806012_20994.cpp:18:22: error: 'n' was not declared in this scope
    printf("%d %d",(m+n)/2,(m-n)/2);
                      ^