Compilare: user.cpp: In function ‘int main()’: user.cpp:26:27: warning: unused variable ‘l’ [-Wunused-variable] int a, b, c, i, j, k, l; ^ user.cpp:27:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ture.in", "r", stdin); ^ user.cpp:28:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ture.out", "w", stdout); ^ user.cpp:29:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &nl, &nc, &nt, &c); ^ user.cpp:32:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &a, &b); ^