sails.cpp: In function 'int main()':
sails.cpp:8:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
freopen("sails.in.5a","r",stdin);
~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
sails.cpp:9:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d",&n);
~~~~~^~~~~~~~~
sails.cpp:10:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
for (int i=0;i<n;i++)scanf("%d%d",&a[i].first,&a[i].second);
~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~