Compilare: user.cpp: In function ‘int main()’: user.cpp:20:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(Y1 > v[i].size()) continue ; ~~~^~~~~~~~~~~~~ user.cpp:24:21: warning: unused variable ‘val’ [-Wunused-variable] int val = *it; ^~~ user.cpp:31:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(v[i].size() < c) printf("0\n"); ~~~~~~~~~~~~^~~ user.cpp:9:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("camion.in", "r", stdin); ^ user.cpp:10:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("camion.out", "w", stdout); ^ user.cpp:12:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &n, &m, &k, &c); ^ user.cpp:18:46: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &X1, &Y1, &X2, &Y2); ^