Compilare: user.c: In function ‘precalc’: user.c:17:9: warning: implicit declaration of function ‘abs’ [-Wimplicit-function-declaration] if(prc[i][j] == -1 || abs(sum1 - sum2) < prc[i][j]){ ^ user.c: In function ‘main’: user.c:33:9: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d%d%d", &n, &m, &p); ^ user.c:36:13: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d", &ma[i][j]); ^