a=int(input()) b=int(input()) c=[] l=[] flag=[] m=5 for i in range(b): d=int(input()) if(d<=a): c.append(d) for i in range(len(c)): e=c[i] if(m==0): print(m) break for k in range(i+1,len(c)): e+=c[k] if (e>a): l.append(a-flag) e=flag continue elif(e==a): m=0 break else: pass if(e<a): l.append(a-e) print(min(l))