Compilare: user.cpp: In function ‘std::pair<int, int> solve(int, int)’: user.cpp:44:28: warning: unused variable ‘n3’ [-Wunused-variable] int v1, v2, n, n2, n3; ^ user.cpp: In function ‘int main()’: user.cpp:85:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("spirt.in", "r", stdin); ^ user.cpp:86:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("spirt.out", "w", stdout); ^ user.cpp:88:26: 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:90:15: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets (sir + 1); ^ /tmp/ccCV2LGk.o: In function `main': user.cpp:(.text.startup+0x84): warning: the `gets' function is dangerous and should not be used.