778A - String Game - CodeForces Solution

s = [i for i in input()]
t = [i for i in input()]
n = len(s)
m = len(t)
arr = [int(x) for x in input().split()]
def helper(mid):
    temp = s.copy()
        i,j = 0,0
    for k in range(mid):
                temp[arr[k]-1] = '0'
                while(i<n or j< m):
        if i== n or j== m:
            break
        if temp[i] == t[j]:
            i += 1
            j +=1
        else:
            i += 1
    if j == m:
        return True
    return False    
l,r= 0,n-1
ans = 0
while(l<= r):
    mid = (l+r)//2
    if helper(mid):
        ans = max(ans, mid)
        l = mid +1
    else:
        r = mid-1
print(ans)