Compilare: user.cpp: In function ‘int main()’: user.cpp:131:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < l[v].size(); i++){ ^ user.cpp:139:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < l[v].size(); i++){ ^ user.cpp:144:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] int s = a[0].size() == r ? c : r; ^ user.cpp:146:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < a[0].size(); j++){ ^ user.cpp:159:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < a[i].size(); j++) ^ user.cpp:91:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("puzzle2.in", "r", stdin); ^ user.cpp:92:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("puzzle2.out", "w", stdout); ^ user.cpp:93:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:95:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^ user.cpp: In function ‘void twoLines()’: user.cpp:32:6: warning: ‘v1’ may be used uninitialized in this function [-Wmaybe-uninitialized] int v1, v2; ^