1 100 
2 90 

입력하면 프로그램이 멈춘다 for문에서 걸리는거같은데 어디서 걸리는지 모르겟다 한번만봐줘

#include <stdio.h>

int main()
{
        int a,a1,b,b1;
        int t,i;
        scanf(\"%d%d%d%d\",&a,&a1,&b,&b1);
        if(a<a1){
                t=a;
                a=a1;
                a1=t;
        }
        if(b<b1){
                t=b;
                b=b1;
                b1=t;
        }

        for(i=a1;i<a;i++){
                if(b==i){
                        for(i=a;i<=100;i++){
                                if(b1==i) {printf(\"cross\");return 0;};
                                

                        }
                        for(i=a1;i>=0;i--){
                                if(b1==i){printf(\"cross\");return 0;};
                                
                        }
                }
                if(b1==i){
                        for(i=a;i<=100;i++){
                                
                                if(b==i){printf(\"cross\");return 0;};

                        }
                        for(i=a1;i>=0;i--){
                                
                                if(b==i){printf(\"cross\");return 0;};
                        }
                }
        }
                
                        printf(\"not cross\");
                return 0;
        }