TLE in PRIME

[eeexort]

This is my simple (IT IS!) code for generating primes. I made it to search from 1 to the sqrt of the no. being tested. I certainly do not know any other way to optimise it(believe me). Plus on my computer and ideone it runs wid no problems. PLEASE HELP! HOW TO AVOID TLE!?

#include<stdio.h>
#include<math.h>
int main()
{
    int s,t,m,n,j,flag,i;
    scanf("%d",&t);
    while(t--)
    {
    scanf("%d%d",&m,&n);
    i = m;
    s = sqrt(i);
    while(i<=n)
    {
               flag=0;
               for(j=1;j<=s;j++)
               {
                 if(i%j==0)
                 flag++;
               }
                 if((flag==2)&&i<=n)
                 printf("%d\n",i);
                 i++;
    }printf("\n");
}
}