boxes.cpp: In function 'long long int delivery(int, int, int, int*)':
boxes.cpp:8:7: error: '_n' was not declared in this scope
n = _n, k = _k, l = _l;
^~
boxes.cpp:8:7: note: suggested alternative: 'n'
n = _n, k = _k, l = _l;
^~
n
boxes.cpp:8:15: error: '_k' was not declared in this scope
n = _n, k = _k, l = _l;
^~
boxes.cpp:8:15: note: suggested alternative: 'k'
n = _n, k = _k, l = _l;
^~
k
boxes.cpp:8:23: error: '_l' was not declared in this scope
n = _n, k = _k, l = _l;
^~
boxes.cpp:8:23: note: suggested alternative: 'l'
n = _n, k = _k, l = _l;
^~
l