R=range
J=lambda:map(int,input().split())
N,M=J()
A=list(J())
E=[[]for i in R(N*2)]
F=[]
for i in R(N):E[i]+=[i+N];F+=[[i,i+N,-A[i]]]
for j in R(M):a,b,c=J();a=a-1+N;E[a]+=[b-1];F+=[[a,b-1,c]]
N*=2
W=[0]+[9**20]*N
for _ in R(N):
	for i,j,w in F:W[j]=min(W[j],W[i]+w)
b=[1]*N
for i,j,w in F:b[i]&=W[j]<=W[i]+w
D=[i for i in R(N)if b[i]<1]
while D:
	for j in E[D.pop()]:D+=[j]*b[j];b[j]=0
print(["inf",-W[N-1]][b[N-1]])