Compilare: main.cpp: In function 'int solve(int, int)': main.cpp:37:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0;i < g[a.x].size();i++){ ~~^~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:50:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("tollroads.in", "r", stdin); ^ main.cpp:51:42: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("tollroads.out", "w", stdout); ^ main.cpp:53:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &n, &m, &q); ^ main.cpp:55:33: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &a, &b, &c); ^ main.cpp:60:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &a, &b); ^