Compilare: user.cpp: In function ‘void calc()’: user.cpp:31:6: warning: unused variable ‘prv’ [-Wunused-variable] int prv , nxt ; ^ user.cpp:31:12: warning: unused variable ‘nxt’ [-Wunused-variable] int prv , nxt ; ^ user.cpp: In function ‘void input()’: user.cpp:96:39: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ( "%d%d%d" , &type , &n , &m ) ; ^ user.cpp:97:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ( "%d" , &COST ) ; ^ user.cpp:98:61: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ( "%d%d%d%d" , &xnorth , &xsouth , &ywest , &yeast ) ; ^ user.cpp:102:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ( "%d" , &a[ i ][ j ] ) ; ^ user.cpp: In function ‘int main()’: user.cpp:143:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ( "fence.in" , "r" , stdin ) ; ^ user.cpp:144:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ( "fence.out" , "w" , stdout ) ; ^