Compilare: user.cpp: In function ‘bool solve(int, int)’: user.cpp:48:13: warning: unused variable ‘a’ [-Wunused-variable] int a = ((1 << bit) & last[i - 1]) > 0; ^ user.cpp:49:13: warning: unused variable ‘b’ [-Wunused-variable] int b = ((1 << where) & last[i - 1]) > 0; ^ user.cpp:50:13: warning: unused variable ‘c’ [-Wunused-variable] int c = ((1 << bit) & M[i - 1]) > 0; ^ user.cpp:51:13: warning: unused variable ‘d’ [-Wunused-variable] int d = ((1 << where) & M[i - 1]) > 0; ^ user.cpp: In function ‘int main()’: user.cpp:72:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sortnet.in", "r", stdin); ^ user.cpp:73:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sortnet.out", "w", stdout); ^ user.cpp:75:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d\n", &n, &m); ^ user.cpp:80:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("<%d,%d> ", &x, &y); ^