Compilare: main.cpp: In function 'int main()': main.cpp:43:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<succ[u.x][u.y].size(); i++){ ~^~~~~~~~~~~~~~~~~~~~~~ main.cpp:22:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] { freopen("memcpy.in", "r", stdin); ^ main.cpp:23:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("memcpy.out", "w", stdout); ^ main.cpp:25:54: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d%d%d", &n, &m, &x1, &y1, &x2, &y2); ^