Compilare: main.cpp: In function 'void dfs(int, int, int)': main.cpp:38:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<arcs[x].size(); ++i) ~^~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:75:27: warning: format '%d' expects argument of type 'int', but argument 2 has type 'std::vector<std::vector<int> >::size_type {aka long unsigned int}' [-Wformat=] printf("%d\n", res.size()); ^ main.cpp:76:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<res.size(); ++i) { ~^~~~~~~~~~~ main.cpp:78:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<res[i].size(); ++j) ~^~~~~~~~~~~~~~ main.cpp:79:13: warning: this 'if' clause does not guard... [-Wmisleading-indentation] if (j == 0 || res[i][j] != res[i][j-1]) ^~ main.cpp:81:3: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'if' printf("\n"); ^~~~~~ main.cpp:54:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("biconex.in", "r", stdin); ^ main.cpp:55:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("biconex.out", "w", stdout); ^ main.cpp:58:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ main.cpp:64:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^