Compilare: main.cpp: In function 'int main()': main.cpp:26:18: warning: unused variable 'j' [-Wunused-variable] int n, m, i, j, x, y ; ^ main.cpp:22:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("drum6.in","r",stdin) ; ^ main.cpp:24:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("drum6.out","w",stdout) ; ^ main.cpp:30:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n ,&m) ; ^