Compilare: user.cpp: In function ‘void readdata()’: user.cpp:30:40: warning: format ‘%ld’ expects argument of type ‘long int*’, but argument 3 has type ‘int*’ [-Wformat=] scanf("%d %ld %d %d\n", &n, &m, &X, &Y); ^ user.cpp:29:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(infile, "r", stdin); ^ user.cpp:30:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %ld %d %d\n", &n, &m, &X, &Y); ^ user.cpp:35:39: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %ld\n", &x, &y, &z); ^ user.cpp: In function ‘void writedata()’: user.cpp:50:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(outfile, "w", stdout); ^