Compilare: user.cpp: In function ‘int main()’: user.cpp:52:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (x = 0; x<muchii[c1].size(); x++) ^ user.cpp:63:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (x = 0; x<muchii[c1].size(); x++) ^ user.cpp:64:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (y = 0; y<muchii[c2].size(); y++) ^ user.cpp:79:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i<muchii[c2].size() && (muchii[muchii[c2][i]].size()>3 || viz[muchii[c2][i]] == true)) i++; ^ user.cpp:94:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i<muchii[c3].size() && (muchii[muchii[c3][i]].size()>3 || viz[muchii[c3][i]] == true)) i++; ^ user.cpp:107:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (x = 0; x<muchii[c1].size(); x++) ^ user.cpp:108:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (y = 0; y<muchii[c2].size(); y++) ^ user.cpp:25:30: warning: unused variable ‘c4’ [-Wunused-variable] int c1 = 0, c2 = 0, c3 = 0, c4 = 0; ^ user.cpp:12:35: 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:13:37: 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:17:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:20:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^