how to reduce time taken by following program....getting tle error

#include<stdio.h>
#include<math.h>
void check(int num)
{
int i,flag;
if(num==2)
{
printf("2\n");
}
for(i=2;i<=((int)(sqrt(num))+1);i++)
{
if(num==1);
else if(num%i==0)
{
flag=1;
break;
}
else
{
flag=0;
}
}
if(flag==0)
{
printf("%d\n",num);
}
}
int main()
{
int a[10],b[10],n,j,i,k;
scanf("%d",&n); //no. of test
for(i=0;i<n;++i)
{
scanf("%d %d",&a[i],&b[i]);
} 
for(k=0;k<n;k++)
{for(j=a[k];j<=b[k];j++)
{
check(j);
}
}

return 0;
}