import sys
input = sys.stdin.readline
INF = 10**18
class SegmentTree:
def __init__(self, L):
N = 1
n = len(L)
while N < n:
N *= 2
Tree = [INF]*(2*N)
for i in range(n):
Tree[N + i] = L[i]
for i in range(N - 1, 0, -1):
Tree[i] = min(Tree[2*i], Tree[2*i+1])
self.N = N
self.Tree = Tree
def point_update(self, i, x):
idx = self.N + i
self.Tree[idx] = x
idx //= 2
while idx >= 1:
self.Tree[idx] = min(self.Tree[2*idx], self.Tree[2*idx+1])
idx //= 2
def first_smaller_than_rec(self, v, tl, tr, l, r, x):
"""
Segment tree min.
Cherche le plus petit i dans [l,r] tq a[i] <= x
"""
if tl > r or tr < l:
return -1
if self.Tree[v] > x:
return -1
if tl == tr:
return tl
tm = (tl + tr) // 2
left = self.first_smaller_than_rec(2*v, tl, tm, l, r, x)
if left != -1:
return left
return self.first_smaller_than_rec(2*v+1, tm+1, tr, l, r, x)
# Lecture des entrées
N, Q = map(int, input().split())
stops = [INF]*N
seg = SegmentTree(stops)
for _ in range(Q):
line = input().split()
if line[0] == 'M':
X = int(line[1])
A = int(line[2])
seg.point_update(A-1, X)
else: # 'D'
Y = int(line[1])
B = int(line[2])
res = seg.first_smaller_than(B-1, N-1, Y)
if res == -1:
print(-1)
else:
print(res+1) # convertir en 1-based
