OJ Board

I code this and got time limit exeed
can anyone help me......
#include <stdio.h>

int main(){
long int n,t1,t2,i,a;
scanf("%ld",&n);
for(i=1;i<=n;i++){
scanf("%ld%ld",&t1,&t2);
long int k=0;
for(;t1<=t2;t1++){
for(a=2;a<=t1;a++){
if(a==t1)
break;
if(t1%a==0)
break;
}
if(a==t1){

long ...