Compilare: main.cpp: In function 'void exp(std::vector<std::vector<double> >&, int)': main.cpp:8:12: warning: variable 'aux' set but not used [-Wunused-but-set-variable] double aux[4][4]; ^~~ main.cpp: In function 'void solve()': main.cpp:60:12: warning: unused variable 'mat' [-Wunused-variable] double mat[4] = {0, c - k, -k, -k}; ^~~ main.cpp: In function 'int main()': main.cpp:77:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("abcacm.in", "r", stdin); ^ main.cpp:78:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("abcacm.out", "w", stdout); ^