//set many funcs template
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#define inf 1072114514
#define llinf 4154118101919364364
#define mod 1000000007
int max(int a,int b){if(a>b){return a;}return b;}
int min(int a,int b){if(a<b){return a;}return b;}
int zt(int a,int b){return max(a,b)-min(a,b);}
int round(int a,int b){if((a%b)*2 >= b){return (a/b)+1;}return a/b;}
int ceil(int a,int b){if(a%b==0){return a/b;}return (a/b)+1;}
int gcd(int a,int b){int c;while(b!=0){c=a%b;a=b;b=c;}return a;}
int lcm(int a,int b){int c=gcd(a,b);a/=c;return a*b;}
int nCr(int a,int b){int i,r=1;for(i=1;i<=b;i++){r*=(a+1-i);r/=i;}return r;}
int fact(int a){int i,r=1;for(i=1;i<=a;i++){r*=i;}return r;}
int pow(int a,int b){int i,r=1;for(i=1;i<=b;i++){r*=a;}return r;}
long long llmax(long long a,long long b){if(a>b){return a;}return b;}
long long llmin(long long a,long long b){if(a<b){return a;}return b;}
long long llzt(long long a,long long b){return llmax(a,b)-llmin(a,b);}
long long llround(long long a,long long b){if((a%b)*2 >= b){return (a/b)+1;}return a/b;}
long long llceil(long long a,long long b){if(a%b==0){return a/b;}return (a/b)+1;}
long long llgcd(long long a,long long b){long long c;while(b!=0){c=a%b;a=b;b=c;}return a;}
long long lllcm(long long a,long long b){long long c=llgcd(a,b);a/=c;return a*b;}
long long llnCr(long long a,long long b){long long i,r=1;for(i=1;i<=b;i++){r*=(a+1-i);r/=i;}return r;}
long long llfact(long long a){long long i,r=1;for(i=1;i<=a;i++){r*=i;}return r;}
long long llpow(long long a,long long b){long long i,r=1;for(i=1;i<=b;i++){r*=a;}return r;}
double dbmax(double a,double b){if(a>b){return a;}return b;}
double dbmin(double a,double b){if(a<b){return a;}return b;}
double dbzt(double a,double b){return dbmax(a,b)-dbmin(a,b);}
int sortfncsj(const void *a,const void *b){if(*(int *)a>*(int *)b){return 1;}if(*(int *)a==*(int *)b){return 0;}return -1;}
int sortfnckj(const void *a,const void *b){if(*(int *)a<*(int *)b){return 1;}if(*(int *)a==*(int *)b){return 0;}return -1;}
int llsortfncsj(const void *a,const void *b){if(*(long long *)a>*(long long *)b){return 1;}if(*(long long *)a==*(long long *)b){return 0;}return -1;}
int llsortfnckj(const void *a,const void *b){if(*(long long *)a<*(long long *)b){return 1;}if(*(long long *)a==*(long long *)b){return 0;}return -1;}
int dbsortfncsj(const void *a,const void *b){if(*(double *)a>*(double *)b){return 1;}if(*(double *)a==*(double *)b){return 0;}return -1;}
int dbsortfnckj(const void *a,const void *b){if(*(double *)a<*(double *)b){return 1;}if(*(double *)a==*(double *)b){return 0;}return -1;}
int main(void){
long long n,a,b,m,x[256],y[256],i,j,k,p[256][256]={0};
scanf("%lld%lld%lld%lld",&n,&a,&b,&m);
for(i=1;i<=m;i++){
scanf("%lld%lld",&x[i],&y[i]);
}
p[a][0]=1;
for(i=0;i<255;i++){
for(j=1;j<=m;j++){
p[y[j]][i+1]+=p[x[j]][i];
p[y[j]][i+1]%=mod;
p[x[j]][i+1]+=p[y[j]][i];
p[x[j]][i+1]%=mod;
}
}
for(i=0;i<256;i++){
if(p[b][i] != 0){printf("%lld\n",p[b][i]);return 0;}
}
return 0;
}
./Main.c:12:5: warning: conflicting types for built-in function ‘round’
int round(int a,int b){if((a%b)*2 >= b){return (a/b)+1;}return a/b;}
^
./Main.c:13:5: warning: conflicting types for built-in function ‘ceil’
int ceil(int a,int b){if(a%b==0){return a/b;}return (a/b)+1;}
^
./Main.c:18:5: warning: conflicting types for built-in function ‘pow’
int pow(int a,int b){int i,r=1;for(i=1;i<=b;i++){r*=a;}return r;}
^
./Main.c:22:11: warning: conflicting types for built-in function ‘llround’
long long llround(long long a,long long b){if((a%b)*2 >= b){return (a/b)+1;}return a/b;}
^
./Main.c: In function ‘main’:
./Main.c:41:5: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result]
scanf("%lld%lld%lld%lld",&n,&a,&b,&m);
^
./Main.c:43:9: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result]
scanf("%lld%lld",&x[i],&y[i]);
^